bluuebunny/crossref_metadata_2025 huggingface dataset:
Biosynthetic Pathway of Thiamine Pyrophosphate: a Special Reference to the Thiamine Monophosphate-Requiring Mutant and the Thiamine Pyrophosphate-Requiring Mutant of
Escherichia coli
Authors: Nakayama Hideo , Hayashi Ryoji
Published: January 2020

Two types of mutants of
Escherichia coli
were isolated, one of which (mutant 70-23-107) responded to thiamine pyrophosphate, and the other (mutant 70-23-102) to thiamine monophosphate and thiamine pyrophosphate. They were produced by further mutation of a thiamine auxotroph of
E. coli
70-23 with
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine. The parent organism required thiamine because phosphohydroxymethylpyrimidine kinase activity was lacking in this organism, and hydroxymethylpyrimidine pyrophosphate was not permeable through the cell membrane of
E. coli
. Thiamine, thiamine monophosphate, and thiamine pyrophosphate were all equally active for the parent, whereas mutants 70-23-102 and 70-23-107 lost their ability to grow on thiamine. Both mutants differed only in the growth response to thiamine monophosphate: the former could grow on thiamine monophosphate, whereas the latter could not. Experimental results with the newly isolated mutants indicate that in
E. coli
the free form of thiamine is not involved in de novo synthesis of thiamine pyrophosphate, but thiamine monophosphate, an exclusive product formed by the reaction between hydroxymethylpyrimidine pyrophosphate and hydroxyethylthiazole monophosphate, is directly phosphorylated to form thiamine pyrophosphate. Exogenous thiamine, on the other hand, is converted to thiamine pyrophosphate via the intermediate formation of thiamine monophosphate.
l
-Arabinose Isomerase Formation in a Conditional Mutant of Gene
araA
of
Escherichia coli
B/r
Authors: Pauley Judith , Power Joseph , Irr Joseph
Published: January 2020

A temperature-sensitive mutant of
Escherichia coli
in which the synthesis of
l
-arabinose isomerase is blocked during growth at 42 C was found to possess the following properties. (i) The mutation occurred in the structural gene for the isomerase, gene
araA
. (ii) During growth at elevated temperatures the mutant accumulates a product which is a precursor to the active enzyme. (iii) The precursor produced at 42 C is slowly converted to active enzyme at 28 C in the absence of protein and ribonucleic acid synthesis. It is concluded that the mutation results in a change in the structure of isomerase which causes formation of active enzyme to be thermolabile at a step beyond the level of translation.
Location of Acid Phosphatase and β-Fructofuranosidase Within Yeast Cell Envelopes
Authors: Arnold Wilfred N.
Published: January 2020

After 16 hr of incubation in a low-phosphate, aerated medium, bakers' yeast was obtained with a high titer of acid phosphatase (EC 3.1.3.2) and β-fructofuranosidase (EC 3.2.1.26). All of the β-fructofuranosidase and 75% of the acid phosphatase were easily released by mechanical disruption in a French pressure cell. The cell wall suffered a limited number of cracks, but this was sufficient for the co-release of these enzymes. Both enzymes were subject to autolytic release, although correlation was inconclusive because of the relative instability of acid phosphatase. The data are consistent with the bulk of the two enzymes being located in the periplasmic space. Ethylacetate treatments yielded ghosts with high β-fructofuranosidase but low acid phosphatase activities. The surviving acid phosphatase was not representative of that in live cells. It was resistant to release by mechanical disruption and showed a high susceptibility to heat inactivation. The β-fructofuranosidase in live cells and in ethylacetatetreated cells exhibited polydispersity in heat inactivation susceptibility; but the kinetics were indistinguishable, and facile release by mechanical disruption was shown in both cases.
Spin-Labeling Studies on the Membrane of a Facultative Thermophilic Bacillus
Authors: Chan May , Virmani Y. P. , Himes R. H. , Akagi J. M.
Published: January 2020

Spin-labeling studies were conducted to elucidate the rigidity and viscosity of the membrane of a facultative thermophilic bacillus. By employing nitroxide stearate probes, it was observed that this fatty acid was incorporated into the membrane fraction. Electron spin resonance spectroscopy indicated that cells grown at 55 C contained a membrane which was more rigid and viscous than the membrane from cells grown at 37 C.
Characterization of a Stable L-Form ofBacillus subtilis168
Authors: Gilpin Richard W. , Young Frank E. , Chatterjee Anadi N.
Published: January 2020

A stable L-form ofBacillus subtilis168 (sal-1) has been isolated which grows and divides logarithmically in liquid medium with a generation time of 60 min. This mutant does not synthesize cell wall as evidenced by chemical, biochemical, and morphological analyses. Antibiotics which specifically inhibit cell wall biosynthesis do not affect the growth of the L-form. Significant differences exist between the membrane proteins of the bacillary form and the L-form. The relative profile of membrane proteins varies with the salt concentration of the medium in both the L-form and the bacillary form.
Effect on Exclusion of Alterations to the Sex Pilus
Authors: Meyneli Elinor , Ewins Anna
Published: January 2020

Chromosomal genes from an Hfr donor, dependent for their transfer upon the integrated F factor, were not excluded by an F
+
recipient when the donor also carried an F-like R factor, and its sex pili contained, in addition to F pilin, another pilin of a different specificity.
Temperature-Sensitive Mutant of
Escherichia coli
K-12 with an Impaired
d
-Alanine:
d
-Alanine Ligase
Authors: Lugtenberg E. J. J. , van Schijndel-van Dam Arna
Published: January 2020

The temperature-sensitive
Escherichia coli
mutant strain ST-640 lyses at the restrictive temperature except when an osmotic stabilizer or a high concentration of
d
-alanine is present. The presence of
dl
-alanyl-
dl
-alanine does not prevent lysis. The rate of murein synthesis, followed in a wall medium, is decreased at both 30 and 42 C.
d
-Alanyl-
d
-alanine and uridine diphosphate-
N
-acetyl-muramyl (UDP-MurNAc)-pentapeptide are synthesized in decreased amounts, accompanied by accumulation of UDP-MurNAc-tripeptide at 42 C but not at 30 C. Uridine nucleotide precursors leak into the medium, especially out of the mutant cells. This leakage is prevented when NaCl is present. The
d
-alanine:
d
-alanine ligase (ADP) (EC 6.3.2.4) of the mutant strain, assayed in crude extracts, is temperature sensitive. The impaired ligase is relatively resistant to
d
-cycloserine and other inhibitors of the enzyme. Combined genetic and enzymatic results show that the low ligase activity is due to a mutation in the
ddl
gene, the structural gene for
d
-alanine:
d
-alanine ligase.
Purification and Properties of the Adenosine Diphosphoglucose:Glycogen Transglucosylase of
Pasteurella pseudotuberculosis
Authors: Dietzler D. N. , Strominger J. L.
Published: January 2020

The enzyme which catalyzes the transfer of glucosyl residues from adenosine diphospho(ADP)-glucose to glycogen has been partially purified from extracts of
Pasteurella pseudotuberculosis
. In contrast to other glycogen synthetases of this type, guanosine diphospho-glucose had about 5% of the activity of ADP-glucose as a glucosyl donor. Some other properties of the enzyme are described and compared to other bacterial glycogen synthetases.
Resolution of the Nitrate Reductase Complex from the Membrane of
Escherichia coli
Authors: Villarreal-Moguel E. I. , Ibarra V. , Ruíz-Herrera J. , Gitler C.
Published: January 2020

A procedure has been developed whereby the components of the nitrate reductase complex from the membrane of
Escherichia coli
can be extracted by means of a nonionic detergent and separated from each other as discrete elements in an active form. It is not yet clear whether these are the dissociated enzymatic elements or whether they are fragments containing other membrane proteins. In any case, they appeared nearly lipid-free and still active.
Cytochemical Reactions of Human Leprosy Bacilli and Mycobacteria: Ultrastructural Implications
Authors: Fisher Clark A. , Barksdale Lane
Published: January 2020

Leprosy bacilli harvested from freshly biopsied tissue from cases of lepromatous, borderline and histoid leprosy were, in conjunction with
Mycobacterium lepraemurium
and representative mycobacteria, examined cytochemically with and without their pyridine-extractable acid-fastness. Unlike the mycobacteria, unextracted leprosy bacilli failed to give a positive response to the periodic acid Schiff test or to take up Sudan black B, toluidine blue O, alkaline methylene blue or safranin O. Once their acid-fastness was removed with pyridine, leprosy bacilli were stained by all of the foregoing dyes except Sudan black B, under this condition they remained gram positive. While permanent loss of acid-fastness from leprosy bacilli always resulted in a loss of acid hematein-fixing material (Smith-Dietrich-Baker tests), the reverse was not true. Mild aqueous saponification, bromination, or sequential treatment with lipase and phospholipase D resulted in a loss of acid hematein-positivity but not acid-fastness. After pyridine extraction, bromination, or aqueous saponification, true mycobacteria lost neither their acid hematein-positivity nor their acid-fastness. The acid hematein-positive material and the acid-fastness of both leprosy bacilli and mycobacteria were lost after treatment with alkaline ethanol. These cytochemical findings are discussed in the light of what is known of the ultrastructure of leprosy bacilli and mycobacteria, and of the occurrence of a
dl
-3, 4-dihydroxyphenylalanine oxidase in leprosy bacilli but not in mycobacteria. An effort is made to explain the rather unique cytochemical properties of leprosy bacilli. Since pyridine-extractable acid-fastness (and acid hematein-positivity) serve to distinguish human leprosy bacilli from
M. lepraemurium
, one or the other, or both, are suggested as bases for differentiating these two organisms in animal experiments designed to show the in vivo propagation of human leprosy bacilli.
Serological Study of Bacterial Flagellar Hooks
Authors: Kagawa Hiroaki , Asakura Sho , Iino Tetsuo
Published: January 2020

Bacterial hooks were partially purified from flagella isolated fromSalmonellaSJ25, by treatment with heat to depolymerize flagellar filaments and withn-butanol and calcium chloride to remove membranes. Antihook serum was obtained from a rabbit inoculated with a preparation of hooks. The serum contained antibodies directed against the flagellar filament and cell membrane. These antibodies could be removed from the serum by absorption with purified flagellar filaments and cells of a nonflagellated mutant strain. It was shown by electron microscopy that anti-SJ25-hook antibody reacts with hooks from a number of strains ofSalmonellawhich differed from SJ25 in H and O antigens, flagellar shape, and motility. Hooks possessed by various strains ofSalmonellahave a common antigenicity. In addition, anti-SJ25-hook cross-reacted with hooks fromEscherichia coliW3110 but did not react at all which those from strains ofSerratia, Proteus, Aerobacter, andKlebsiella. It is well known that bacteria stop moving upon addition of antiflagella serum to the medium. However, the addition of purified antihook was found to have little effect on motility. At physiological ionic strength and pH, flagellin (Salmonella) can polymerize into flagellar filaments only in the presence of seeds. It was shown that a crude preparation of hooks was able to initiate in vitro polymerization of flagellin.
Nuclear Deoxyribonucleic Acid-Dependent Ribonucleic Acid Polymerases from
Saccharomyces cerevisiae
Authors: Sebastian Jesus , Bhargava Madhu M. , Halvorson Harlyn O.
Published: January 2020

Two deoxyribonucleic acid (DNA)-dependent ribonucleic acid (RNA) polymerases (I, II) have been solubilized from isolated
Saccharomyces cerevisiae
nuclei. The enzymes can be separated by chromatography on
O
-diethylaminoethyl Sephadex. Both enzymes are active with high-molecular-weight nuclear yeast DNA, although RNA polymerase I has a higher affinity for polydeoxy-adenylic-thymidylic acid and RNA polymerase II for denatured DNA. RNA polymerase I is active only with manganese. α-Amanitin inhibits only the activity of RNA polymerase II.
In Vivo Complementation Between Wild-Type and Mutant β-Galactosidase in
Escherichia coli
Authors: Hall Barry G.
Published: January 2020

A comparison of the specific activity of wild-type β-galactosidase synthesized in a
lacZ
−
/
lacZ
+
heterogenote has shown that there is 60% more activity in the heterogenote's enzyme than can be accounted for by wild-type subunits alone. It is concluded that wild type β-galactosidase subunits can complement mutant subunits.
Carrier-Mediated Transport of Folate in a Mutant of
Pediococcus cerevisiae
Authors: Shavit Frederika Mandelbaum , Grossowicz Nathan
Published: January 2020

A mutant strain of
Pediococcus cerevisiae
(
P. cerevisiae
/PteGlu) was isolated which grows on low-folate (PteGlu) concentrations (200 pg/ml). The growth response of the parent and mutant strains to folinate (5-CHO-H
4
PteGlu) was the same. The transport of
14
C-PteGlu by
P. cerevisiae
/PteGlu was temperature-dependent (Q
10
between 27 C and 37 C was about 2), energy-dependent, and pH-dependent and was inhibited by iodoacetate, 2,4-dinitrophenol, potassium fluoride, and sodium azide. The uptake obeyed saturation kinetics with an apparent

K
m

of 6.6 × 10
−6
M and

V
max

of 4.0 × 10
−10
mol per min per mg (dry weight). At the steady state the intracellular concentration of PteGlu was 120-fold higher from that of the medium. Reduced folates like 5-CHO-H
4
PteGlu and methyl-tetrahydrofolate (5-CH
3
-H
4
PteGlu) as well as 2,4-diaminoanalogues (amethopterin and aminopterin) were shown to compete for the PteGlue-carrier.
Evidence for the Existence of an Aerobic Pathway for Synthesis of Monounsaturated Fatty Acids by
Alcaligenes faecalis
Authors: Ghaneker A. S. , Nair P. M.
Published: January 2020

Studies on the composition of total fatty acids of
Alcaligenes faecalis
harvested at different growth phases have been carried out. Ability of the organism to desaturate palmitic and stearic acid has also been tested. The organism contained palmitic (16:0), stearic (18:0), palmitoleic (16:1),
cis
-vaccenic (18:1), cyclopropane (17:▽ and 19:▽), and three hydroxy acids. Increase in cyclopropane acids and corresponding decrease in monounsaturated acids in direct proportion to the age of the culture were observed, whereas other fatty acids remained relatively unaltered. A growing culture of the organism was found to desaturate [
1
-
14
C
]palmitic acid supplied in the medium to hexadecanoic acid. Resting cells desaturated [
1
-
14
C
]palmitic and [
1
-
14
C
]stearic acid giving rise to about 50% of
14
C in the COOH group of corresponding monounsaturated fatty acids.
Changes in Isozyme Patterns Between Monokaryons and Dikaryons of a Bipolar
Coprinus
Authors: Ross Ian K. , Martini Elizabeth M. , Thoman Marilyn
Published: January 2020

Proteins and isozymes of several different classes of enzymes in partially purified protein extracts of monokaryons, dikaryons, and monokaryon mixtures of a bipolar
Coprinus
sp. were separated on polyacrylamide gels by slab electrophoresis. Differences in protein and isozyme spectra were correlated with the operation of the incompatibility factors and with the results of Wang and Raper on
Schizophyllum
. It was concluded that the shift from monokaryon to dikaryon mediated a major change in the nature, quantity, or distribution of the proteins of this
Coprinus
sp.
Excretion of Enterochelin by
exbA
and
exbB
Mutants of
Escherichia coli
Authors: Guterman S. K. , Dann L.
Published: January 2020

Escherichia coli
mutants that are insensitive to colicins B and I hyperproduce and excrete the iron chelator enterochelin, which is an inhibitor of these colicins. These mutants are classified as
exbA
and
exbB
. The
exbA
mutants are chromium sensitive and require iron for growth, and the mutations are located in the
tonB
region at min 25 of the
E. coli
chromosome.
tonB
mutants in which the genome of phage lambda is inserted into the bacterial chromosome within the
tonB
gene also exhibit enterochelin excretion. The
exbB
mutants require methionine and probably result from deletions which are located between min 56 and 58. Colicin insensitivity, enterochelin excretion and methionine auxotrophy are recessive in
exbB
merodiploids. The methionine requirement of
exbB
strains is satisfied by cystathionine or homocysteine, and
exbB
mutants are sensitive to ethionine.
Polyamines of
Pseudomonas acidovorans
Authors: Karrer E. , Bose R. J. , Warren R. A. J.
Published: January 2020

Pseudomonas acidovorans
contains putrescine, 2-hydroxyputrescine, and spermidine.
Budding in the Dimorphic Fungus
Phialophora dermatitidis
Authors: Grove Stanley N. , Oujezdsky Karen B. , Szaniszlo Paul J.
Published: January 2020

Ultrastructural comparisons of yeast and hyphal bud formation in
Phialophora dermatitidis
reveal that bud initiation is characterized by a blastic rupture of the outer portion of the yeast or hyphal wall and the emergence of a bud protuberance through the resulting opening. The wall of the emerging bud is continuous, with only an inner wall layer of the parental yeast or hypha. The outer, ruptured portion of the parental wall typically forms a collar around the constricted emergence region of the developing bud. The cytoplasm within the very young emerging bud invariably contains a small number of membrane-bound vesicles. The septum formed between the daughter bud and the parental yeast or hypha is a complete septum devoid of a septal pore, septal pore plug, or any associated Woronin bodies characteristic of simple septa of the moniliform or true hyphae. These observations suggest that yeast bud formation and lateral hyphal bud formation in the dimorphic fungus
P. dermatitidis
involve a growth process which occurs identically in both the yeast and mold phase of this human pathogenic organism.
Edman Degradation on In Vitro Biosynthesized Peptidoglycans from
Staphylococcus epidermidis
Authors: Hilderman R. H. , Riggs H. G.
Published: January 2020

Edman degradations were performed on the pentapeptide bridges of peptidoglycans which were biosynthesized in vitro by using six different species of seryl-transfer ribonucleic acid (tRNA). The ratio of glycine to serine in each of the five bridge positions varied with the concentration of crude glycyl-tRNA contained in the reaction mixtures, and serine appeared to be incorporated in a random manner. No single species of seryl-tRNA could be identified as the one active in in vivo pentapeptide bridge synthesis; however, it can be speculated that seryl-tRNA(s) from category I could be involved in the in vivo nonrandom incorporation of serine in the bridge.
Specific Inhibitors of Ammonia Oxidation in
Nitrosomonas
Authors: Hooper Alan B. , Terry Kathleen R.
Published: January 2020

The following compounds or treatments have been shown to inhibit the oxidation of ammonia, but not the oxidation of hydroxylamine in cells of
Nitrosomonas
: (i) metal-binding agents such as allylthiourea or potassium cyanide; (ii) compounds such as SKF 525 which interact with cytochrome P-450 of mammalian microsomes; (iii) carbon monoxide; (iv) inhibitors of catalase, peroxidase, and amine oxidases such as thiosemicarbazide, ethylxanthate, and iproniazid, respectively; (v) uncouplers of oxidative phosphorylation such as
m
-chlorocarbonylcyanidephenylhydrazone; (vi) electron acceptors such as phenazine methosulfate; (vii) compounds such as methanol or N
2
O which react with free radicals; and (viii) illumination with 420 lux (5,000 foot candles) of light.
Localization of Trehalase in the Ascospores ofNeurospora: Relation to Ascospore Dormancy and Germination
Authors: Hecker Lanny I. , Sussman Alfred S.
Published: January 2020

An association of trehalase with the innermost wall (endosporium) of ascospores ofNeurosporais suggested, because this enzyme could be lyophilized in the presence of various wall components and heated in this dried state at 65 C without loss of activity. Ground ascospore walls, purified mycelial walls, a wall fraction consisting of protein, glucan and polygalactosamine, or bovine serum albumin stabilize trehalase under these conditions. No other substances tested protected as well as the above materials. Immunofluorescent labeling of trehalase shows that it is localized in the endosporium. Therefore, it is most probable that in dormant ascospores ofNeurospora, trehalase, and its substrate, trehalose, are physically separated. Trehalose is located in the cytoplasm, whereas trehalase resides within the protein and carbohydrate matrix of the innermost major cell wall layer of the ascospore. The association with the cell wall protects the enzyme against the heating which is necessary to activate germination. Activation, whether by heat or chemical treatment (furfural), probably involves an increase in the permeability of the ascospore plasma membrane allowing trehalose to diffuse to the vicinity of its hydrolase, thereby providing the energy and intermediates for germination.
Physiological Effects of Menaquinone Deficiency in
Bacillus subtilis
Authors: Farrand S. K. , Taber H. W.
Published: January 2020

Several aspects of the respiratory physiology of a mutant of
Bacillus subtilis
deficient in menaquinone-7 (MK-7) and in cytochromes were investigated. The mutant, an aromatic amino acid auxotroph blocked at dehydroshikimate reductase, is unable to synthesize MK-7 unless grown in the presence of the common aromatic amino acid intermediate, shikimate. The inability to synthesize MK-7 prevents the mutant from expressing the normal postexponentialphase cytochrome phenotype. When grown in the presence of shikimate, normal levels of these electron transport components are formed. It was found that the intracellular concentration of MK-7 could be predictably regulated by growing the cells with known concentrations of exogenous shikimate. When the mutant was grown under conditions where MK-7 biosynthesis was severely limited, there was a decrease in oxygen uptake and in membrane-associated reduced nicotinamide adenine dinucleotide (NADH) oxidase and succinate oxidase activity. NADH oxidase, but not succinoxidase, could be restored in membrane preparations by the addition of menadione to the reaction mixture. Reduced-minus-oxidized cytochrome difference spectra indicate that an MK-7 deficiency limits electron flow through the cytochrome chain. Furthermore, oxidation-reduction patterns suggest that MK-7 functions between the primary dehydrogenases and the cytochromes. Although the mutant is asporogenous when grown under conditions where MK-7 biosynthesis is limited, the inability to sporulate does not appear to result from lesions in the electron transport system.
Genetic Mapping of a Mutant Defective in
d, l
-Alanine Racemase in
Bacillus subtilis
168
Authors: Dul Michael J. , Young Frank E.
Published: January 2020

Genetic analysis of a
d
-alanine requiring mutant (
dal
) of
Bacillus subtilis
reveals that the gene that codes for
d,l
-alanine racemase is linked to
purB
. The order of genes in this region of the chromosome is
pur
B,
pig, tsi, dal
. Thus there are at least two clusters of genes that regulate cell wall biosynthesis in
B. subtilis
.
Chemotaxis Toward Sugars in
Escherichia coli
Authors: Adler Julius , Hazelbauer Gerald L. , Dahl M. M.
Published: January 2020

Using a quantitative assay for measuring chemotaxis, we tested a variety of sugars and sugar derivatives for their ability to attract
Escherichia coli
bacteria. The most effective attractants, i.e., those that have thresholds near 10
−5
M or below, are
N
-acetyl-
d
-glucosamine, 6-deoxy-
d
-glucose,
d
-fructose,
d
-fucose, 1-
d
-glycerol-β-
d
-galactoside, galactitol,
d
-galactose,
d
-glucosamine,
d
-glucose, α-
d
-glucose-1-phosphate, lactose, maltose,
d
-mannitol,
d
-mannose, methyl-β-
d
-galactoside, methyl-β-
d
-glucoside,
d
-ribose,
d
-sorbitol, and trehalose. Lactose, and probably
d
-glucose-1-phosphate, are attractive only after conversion to the free monosaccharide, while the other attractants do not require breakdown for taxis. Nine different chemoreceptors are involved in detecting these various attractants. They are called the
N
-acetyl-glucosamine, fructose, galactose, glucose, maltose, mannitol, ribose, sorbitol, and trehalose chemoreceptors; the specificity of each was studied. The chemoreceptors, with the exception of the one for
d
-glucose, are inducible. The galactose-binding protein serves as the recognition component of the galactose chemoreceptor.
E. coli
also has osmotically shockable binding activities for maltose and
d
-ribose, and these appear to serve as the recognition components for the corresponding chemoreceptors.
Subcellular Localization of the Leucine Biosynthetic Enzymes in Yeast
Authors: Ryan E. D. , Tracy J. W. , Kohlhaw G. B.
Published: January 2020

When baker's yeast spheroplasts were lysed by mild osmotic shock, practically all of the isopropylmalate isomerase and the β-isopropylmalate dehydrogenase was released into the 30,000 ×
g
supernatant fraction, as was the cytosol marker enzyme, glucose-6-phosphate dehydrogenase. α-Isopropylmalate synthase, however, was not detected in the initial supernatant, but could be progressively solubilized by homogenization, appearing more slowly than citrate synthase but faster than cytochrome oxidase. Of the total glutamate-α-ketoisocaproate transaminase activity, approximately 20% was in the initial soluble fraction, whereas solubilization of the remainder again required homogenization of the spheroplast lysate. Results from sucrose density gradient centrifugation of a cell-free particulate fraction and comparison with marker enzymes suggested that α-isopropylmalate synthase was located in the mitochondria. It thus appears that, in yeast, the first specific enzyme in the leucine biosynthetic pathway (α-isopropylmalate synthase) is particulate, whereas the next two enzymes in the pathway (isopropylmalate isomerase and β-isopropylmalate dehydrogenase) are “soluble,” with glutamate-α-ketoisocaproate transaminase activity being located in both the cytosol and particulate cell fractions.
Process of Cellular Division in
Escherichia coli
: Physiological Study on Thermosensitive Mutants Defective in Cell Division
Authors: Ricard Matthieu , Hirota Yukinori
Published: January 2020

Thermosensitive
fts
mutants of
Escherichia coli
belonging to seven previously identified genetic classes (
ftsA
to
ftsG
) were studied from a physiological standpoint. These mutants immediately stopped dividing and formed multinucleated filaments when the temperature was shifted to 41 C. Macromolecular syntheses (deoxyribonucleic acid), ribonucleic acid, cell mass, and murein) continued exponentially for at least 40 to 120 min. The number of surviving bacteria remained constant during the time of incubation, and this number began to decrease exponentially, as the rate of cell mass increase leveled off from the initial rate. The recovery of cell division at 30 C in these filamentous cells was studied after 60 min of incubation at 41 C. The existence of three types of mutants was shown. The
ftsA
and
ftsE
mutants resumed cell division without new protein synthesis;
ftsD
mutants resumed cell division only if new protein synthesis occured, while
ftsB, C, F
and
G
mutants did not resume cell division at all. No alteration in the cell envelope was detected by the method used here, although the
ftsA, B, D, F
and
G
mutations, in contrast with
ftsC
and
E
, caused an increased resistance to penicillin G. It was also shown that the
recA
mutation did not suppress the effect of the
fts
mutations and that none of the lysogenic
fts
mutants induced prophage multiplication while forming filaments. The effects of osmotic pressure and salts which rescue the mutant phenotype is described.
Ultrastructural Study of Crossbands Occurring in the Stalks of
Caulobacter crescentus
Authors: Jones H. C. , Schmidt Jean M.
Published: January 2020

An ultrastructural study of crossbands isolated from
Caulobacter crescentus
Sk1 418 stalks permitted a view of these structures in a plane other than the perpendicular view normally presented in the electron microscope. These crossbands were composed of concentrically arranged, alternating light and dark bands when stained with phosphotungstic acid. Evidence supports the hypothesis that crossbands appear to compose a structural barrier extending the width of the stalk and may function to support unit membrane extending the length of the stalk.
Phycobilisomes from a Blue-Green Alga
Nostoc
Species
Authors: Gray B. H. , Lipschultz C. A. , Gantt E.
Published: January 2020

Phycobilisomes were isolated from a
Nostoc
sp. strain Mac in phosphate buffer (pH 7.0) by treatment with 1% Brij 56 and centrifugation on discontinuous sucrose gradients (2.0, 1.0, 0.5, and 0.25 M in the proportions 6:4:4:10 ml, respectively). Absorption spectra of isolated phycobilisomes showed the presence of phycoerythrin, phycocyanin, and allophycocyanin. The phycobilisome pigments were partially resolved by electrophoresis on acrylamide gels. Stained gels demonstrated that each main protein band corresponded to a pigmented region. The phycobilisomes appeared compact with a rounded surface and flattened base (about 40-nm diameter) at the attachment site to the photosynthetic lamellae. Fixation in glutaraldehyde caused a significant reduction in total pigment absorption, as well as shifts in the absorption maxima, particularly that of phycoerythrin.
Ultrastructure and Capsule ofMycoplasma meleagridis
Authors: Green Frederick , Hanson Robert P.
Published: January 2020

The ultrastructural study ofMycoplasma meleagridisutilized the electron microscope techniques of sectioning, histochemical staining, critical-point drying, and freeze etching. The predominant morphotype was a spherical form ranging in diameter from 200 to 700 nm. The other morphotypes were dumbbell-shaped cells interconnected by membranous tubules, and chains of streptococcal-like cells. These forms suggest replication by binary fission. An extracellular structure in the form of a capsular matrix was observed by staining with ruthenium red and potassium tellurite, and was also seen in specimens prepared by critical-point drying and freeze etching.
Effect of Low-Intensity Light on Growth Response and Bacteriochlorophyll Concentration in
Rhodospirillum rubrum
Mutant C
Authors: Uffen R. L.
Published: January 2020

Photosynthesizing cells of
Rhodospirillum rubrum
mutant C underwent adaptation for growth in low-light conditions. During adaptation there was a transitory increase in the generation time and the bacteriochlorophyll
a
content of the cells.
Isolation of Temperature-Sensitive Membrane Mutants of
Escherichia coli
K-12
Authors: Steenbakkers Johan F. , Broekman J. H. F. F. , Kerkenaar A. , De Haan P. G.
Published: January 2020

Mutants with impaired biosynthesis of unsaturated fatty acids or altered metabolism of the phospholipids were isolated at a rather high frequency from a set of temperature-sensitive lysis mutants. It is suggested that preselection for the lysis phenotype makes it possible to isolate several kinds of mutants affected in the integrity of the cytoplasmic membrane.
Deletion Mapping and Orientation of the Histidine Operon of
Escherichia coli
on a Transducing Bacteriophage
Authors: Avitabile Alessandra , Bruni Carmelo B. , Carlomagno-Cerillo Maria S. , Meyers Marylin , Vigliar Germana , Blasi Francesco
Published: January 2020

The defective prophage φ80
i
λ
c
I
857
dhis
has been mapped through both marker rescue and deletion analysis. Deletions have been isolated which put residual
his
genes close to
trp
genes. Analysis of these deletions shows that the histidine operon on the prophage is oriented clockwise as on the bacterial chromosome, thus opposite to the orientation of the
trp
operon. The presence of the
his
promoter-operator region is inferred by the ability of the prophage-carrying strain to derepress sequentially under conditions in which the histidine concentration is limiting. In addition to
his
, the
gnd
gene is also present on the prophage and is located between
his
and
trp
operons. The bacterial genes are inserted in the right arm of the prophage and substitute for all of the late function genes, except for the first three. These data indicate that the “sense” strand for transcription of the
his
operon in vivo must be the “R” strand.
Factors Affecting the Resistance of
Lactobacillus fermenti
to Lysozyme
Authors: Neujahr Halina Y. , Börstad Birgitta , Logardt Inga-Maj
Published: January 2020

The sensitivity of
Lactobacillus fermenti
ATCC 9338 to lysozyme has its peak during the exponential phase of growth, after the autolytic activity of the organism has begun to decline. Cells from the stationary growth phase are resistant to lysozyme. The two lytic activities require different ionic conditions for their functioning; they appear mutually exclusive. Incubation with trypsin renders cells from all growth phases sensitive to lysozyme. The effect of trypsin is independent of the presence of lysozyme and vice versa, as demonstrated by use of trypsin inhibitors. Cells from early stationary phase of growth require higher temperature for optimum lysozyme action than do those from the exponential growth phase.
Induction and Repression in the
S
-Adenosylmethionine and Methionine Biosynthetic Systems of
Saccharomyces cerevisiae
Authors: Ferro A. J. , Spence K. D.
Published: January 2020

Two methionine biosynthetic enzymes and the methionine adenosyltransferase are repressed in
Saccharomyces cerevisiae
when grown under conditions where the intracellular levels of
S
-adenosylmethionine are high. The nature of the co-repressor molecule of this repression was investigated by following the intracellular levels of methionine,
S
-adenosylmethionine, and
S
-adenosylhomocysteine, as well as enzyme activities, after growth under various conditions. Under all of the conditions found to repress these enzymes, there is an accompanying induction of the
S
-adenosylmethionine-homocysteine methyltransferase which suggests that this enzyme may play a key role in the regulation of
S
-adenosylmethionine and methionine balance and synthesis.
S
-methylmethionine also induces the methyltransferase, but unlike
S
-adenosylmethionine, it does not repress the methionine adenosyltransferase or other methionine biosynthetic enzymes tested.
Effects of Leucine Starvation on Control of Ribonucleic Acid Synthesis in Strains of
Bacillus subtilis
Differing in Deoxyribonucleic Acid Regulation
Authors: Thomas Julian E. , Copeland James C.
Published: January 2020

When starved for leucine, strains of
Bacillus subtilis
do not complete chromosome replication to the terminus. The amount of deoxyribonucleic acid (DNA) made poststarvation is characteristic of the strain. In this study, four strains differing in their DNA response were examined for ribonucleic acid (RNA) regulation during leucine starvation. Each of the strains was judged to be stringent for RNA control based on the amount of RNA made poststarvation. Sucrose gradient profiles on RNA made with and without leucine starvation support this conclusion. Accumulation of guanosine tetraphosphate during leucine starvation showed no correlation with the amount of DNA synthesized. We concluded that modulation control of DNA synthesis during leucine starvation is independent of RNA control.
Identification of the Amide-Linked Fatty Acids of
Acholeplasma axanthum
S743 as
d
(–)3-Hydroxyhexadecanoate and Its Homologues
Authors: Mayberry William R. , Smith P. F. , Langworthy Thomas A. , Plackett Philip
Published: January 2020

The amide-linked fatty acids of the sphingolipids of
Acholeplasma axanthum
S743 are predominantly hydroxy acids. These acids were shown by gas-liquid chromatography, mass spectrometry, and polarimetry to be the
d
(–)3-hydroxy fatty acids. The predominant component of the mixture was 3-hydroxyhexadecanoate (β-hydroxypalmitate, hydroxy [h] 16:0) followed by h 20Δ (Δ = unsaturated), h14:0, h12:0, and h18Δ in decreasing order of concentration. The fatty acid profile indicates that these β-hydroxy acids possibly arise from elongation of the fatty acids supplied in the growth medium.
Kinetics of Phosphate Incorporation into Adenosine Triphosphate and Guanosine Triphosphate in Bacteria
Authors: Lutkénhaus Joseph , Ryan John , Konrad Michael
Published: January 2020

Escherichia coli
cells were labeled with
33
PO
4
for several generations and then
32
PO
4
was added, samples were taken at various times, and adenosine triphosphate (ATP) and guanosine triphosphate (GTP) were purified from an acid extract. The ratio of
32
P/
33
P in each of the six phosphate species was determined and compared to the ratio expected at isotopic steady state. The rate constants of the simplest network of pools which could explain the data, and were consistent with metabolic pathways, were then calculated. In the range of times studied (30 to 3,000 s at 21.5 C) the following generalizations can be made. (i) The γ-phosphate at ATP requires 2,200 s to achieve 50% of its final specific activity and behaves as if it were exchanging with another species 4.4 times as large, with this other species turning over in 540 s. (ii) The β-phosphate of ATP and the γ-phosphate of GTP are in equilibrium with the γ-phosphate of ATP. (iii) The specific activity of the γ-phosphate of GTP lags 66 s behind the γ-phosphate of ATP. (iv) The α-phosphates of ATP and GTP have equal specific activities which lag far behind the other four phosphates. A single precursor pool with a turnover time of 416s fits the data best, although a fair fit can be obtained assuming several sequential precursor pools with much shorter turnover times. These findings are consistent with known biosynthetic pathways and the probable flows through them, including the relationship of nucleotide biosynthesis to ribonucleic acid synthesis and turnover.
Loss of an Essential Function of
Escherichia coli
by Deletions in the
thyA
Region
Authors: Chung Shiau-Ta , Greenberg G. Robert
Published: January 2020

In an attempt to obtain deletions in the
thyA
gene, an abnormal lysogen of λ having the prophage inserted between the
thyA
and
lysA
genes was induced, and the surviving cured cells were examined for Thy
−
and Lys
−
mutants. In nearly 10,000 cured cells, 184 Lys
−
but no Thy
−
mutants were found. At the same time, the induced λ phage contained an approximately equivalent number of λ
thyA
+
and λ
lysA
+
transducing particles. By contrast, in a strain with the genotype F′
thyA
−
lysA
+
/
thyA
+
lysA
+
, induction of the abnormal λ lysogen gave rise to many Thy
−
mutants in the cells cured of the prophage. In these Thy
−
mutants it was not possible to eliminate the episome with acridine orange, although the episome could be removed in control cultures with a
thyA
+
allele in the resident gene. Therefore, it was suggested that deletion of a gene in the region of the chromosome from the position of the insertion of the λ prophage through the
thyA
gene caused loss of an essential and diffusible function.
Immersion Refractometry of Isolated Bacterial Cell Walls
Authors: Marquis Robert E.
Published: January 2020

Immersion-refractometric and light-scattering measurements were adapted to determinations of average refractive indices and physical compactness of isolated bacterial cell walls. The structures were immersed in solutions containing various concentrations of polymer molecules that cannot penetrate into wall pores, and then an estimate was made of the polymer concentration or the refractive index of the polymer solution in which light scattering was reduced to zero. Because each wall preparation was heterogeneous, the refractive index of the medium for zero light scattering had to be estimated by extrapolation. Refractive indices for walls suspended in bovine serum albumin solutions ranged from 1.348 for walls of the rod form of
Arthrobacter crystallopoietes
to 1.382 for walls of the teichoic acid deficient, 52A5 strain of
Staphylococcus aureus
. These indices were used to calculate approximate values for solids content per milliliter, and the calculated values agreed closely with those estimated from a knowledge of dextran-impermeable volumes per gram, dry weight, of the walls. When large molecules such as dextrans or serum albumin were used for immersion refractometry, the refractive indices obtained were for entire walls, including both wall polymers and wall water. When smaller molecules that can penetrate wall pores to various extents were used with
Micrococcus lysodeikticus
walls, the average, apparent refractive index of the structures increased as the molecular size of probing molecules was decreased. It was possible to obtain an estimate of 1.45 to 1.46 for the refractive index of wall polymers, predominantly peptidoglycans in this case, by extrapolating the curve for refractive index versus molecular radius to a value of 0.2 nm, the approximate radius of a water molecule. This relatively low value for polymer refractive index was interpreted as evidence in favor of the amorphous, elastic model of peptidoglycan structure and against the crystalline, rigid model.
Inhibition of Deoxyribonucleic Acid Synthesis and Bud Formation by Nalidixic Acid in
Hyphomicrobium neptunium
Authors: Weiner Ronald M. , Blackman Marcia A.
Published: January 2020

The relationship between chromosome replication and morphogenesis in the budding bacterium
Hyphomicrobium neptunium
has been investigated. Nalidixic acid was found to completely inhibit deoxyribonucleic acid synthesis, but not ribonucleic acid synthesis. The antibiotic was bacteriostatic to the organism for the initial 5 h of exposure; thereafter it was bacteriocidal. Observation of inhibited cultures revealed cells that had produced abnormally long stalks, but no buds. These results indicate that bud formation is coupled to chromosome replication in
H. neptunium
. They do not exclude the possibilities that cross wall formation and bud separation may also be coupled to chromosome replication.
Mutants of Group D
1
Salmonella
Carrying the Somatic Antigen of Group A Organisms: Evidence for the Lack of Cytidine Diphosphate Paratose-2-Epimerase Activity
Authors: Sasaki Terukatsu , Uchida Takahiro
Published: January 2020

The mutant strains of
Salmonella durban
that possessed O antigen 2, 12 of group A
Salmonella
were defective in the cytidine diphosphate paratose-2-epimerase activity. The enzyme preparation of the mutant strains catalyzed the conversion of cytidine diphosphate glucose into cytidine diphosphate paratose but not into cytidine diphosphate tyvelose. The defect in the epimerase activity was also confirmed by the use of purified cytidine diphosphate paratose as a substrate. The specificity of dideoxyhexosyl transferase catalyzing the formation of the group-specific determinant is discussed.
Tryptophan Biosynthesis from Indole-3-Acetic Acid by Anaerobic Bacteria from the Rumen
Authors: Allison Milton J. , Robinson I. M. , Baetz A. L.
Published: January 2020

Microbes in ruminal contents incorporated
14
C into cells when they were incubated in vitro in the presence of [
14
C]carboxyl-labeled indole-3-acetic acid (IAA). Most of the cellular
14
C was found to be in tryptophan from the protein fractions of the cells. Pure cultures of several important ruminal species did not incorporate labeled IAA, but all four strains of
Ruminococcus albus
tested utilized IAA for tryptophan synthesis.
R. albus
did not incorporate
14
C into tryptophan during growth in medium containing either labeled serine or labeled shikimic acid. The mechanism of tryptophan biosynthesis from IAA is not known but appears to be different from any described biosynthetic pathway. We propose that a reductive carboxylation, perhaps involving a low-potential electron donor such as ferredoxin, is involved.
Characterization of Three Plasmid Deoxyribonucleic Acid Molecules in a Strain of
Streptococcus faecalis
: Identification of a Plasmid Determining Erythromycin Resistance
Authors: Clewell D. B. , Yagi Y. , Dunny G. M. , Schultz S. K.
Published: January 2020

Three plasmids designated α, β, and γ, distinguishable by their molecular weights (6, 17, and 34 million, respectively) were isolated from
Streptococcus faecalis
strain DS-5 (ATCC 14508). Derivatives of this strain “cured” for erythromycin resistance lacked the β-plasmid. In the parent strain the β-plasmid was estimated to be present to the extent of one to two copies per chromosomal genome equivalent whereas the α- and γ-plasmids were about nine and five copies, respectively.
Genetic Analysis of the γ-Aminobutyrate Utilization Pathway in
Escherichia coli
K-12
Authors: Dover Shabtay , Halpern Yeheskel S.
Published: January 2020

The control mutation that results in a concomitant severalfold increase in the activities of γ-aminobutyrate-α-ketoglutarate transaminase (GSST, EC 2.6.1.19) and succinic semialdehyde dehydrogenase (SSDH, EC 1.2.1.16), leading to the acquisition of the ability to utilize γ-aminobutyrate (GABA) as the sole source of nitrogen by
Escherichia coli
K-12 mutants, was mapped by mating and transduction with P1
kc
. The locus affected,
gabC
, is approximately 48% co-transduced with the
thyA
gene, located at min 55 of the
E. coli
K-12 chromosome. The structural gene of the first enzyme in the GABA pathway, GSST, was mapped by interrupted mating, using one of the GSST-less mutants, DB742, isolated in this work. The mutated locus,
gabT
, is situated at about min 73 of the
E. coli
chromosome, close to the
gltC
gene. Genetic evidence concerning the sensitivity of the enzymes of the GABA pathway to catabolite repression under different physiological conditions suggests that the two structural genes of the GABA regulon do not constitute one operon.
Effect of Viscosity on Bacterial Motility
Authors: Schneider W. R. , Doetsch R. N.
Published: January 2020

The behavior of a number of motile flagellated bacteria toward viscosity characteristics of their fluid environments was observed. All showed an increase in velocity (micrometers per second) in more viscous solutions. Velocity reached a maximum at a characteristic value, however, and thereafter decreased with higher viscosities. Peritrichously flagellated bacteria had maximum velocities at higher viscosities than polarly flagellated bacteria. Effects of temperature, and possible utilization of chemical constituents in the viscous solutions, were studied and found to be negligible factors under the experimental conditions used. Different agents produced the same phenomenon, thus indicating that there probably were no chemically induced metabolic effects. Loss of available water and the possibility of a variable energy supply to the flagellar propulsive system were considered but are believed minimal. Theoretically derived thermodynamic equations were utilized and suggest that the conformation of the flagellar helix affects efficiency of propulsion. Such a relationship between helix waveform and velocity was experimentally observed with
Thiospirillum jenese
.
Effect of Temperature on the Growth and Cell Wall Chemistry of a Facultative Thermophilic
Bacillus
Authors: Novitsky Thomas J. , Chan May , Himes Richard H. , Akagi J. M.
Published: January 2020

The morphology and cell wall composition of
Bacillus coagulans
, a facultative thermophile, were examined as a function of growth temperature. The morphology of the organism varied when it was grown at different temperatures; at 37 C the organism grew as individual cells which increased in length with increasing growth temperature. At 55 C it grew in long chains of cells. Cell wall prepared from cells grown at 37 C contained 44% teichoic acid by weight, whereas cells grown at 55 C contained 29% teichoic acid. Teichoic acid from these cells was a polymer of glycerol phosphate containing galactose and ester alanine. The ratio of ester alanine to phosphate was significantly higher in cell walls and teichoic acid from 37 C-grown cells compared with those from 55 C-grown cells. Other differences observed were that cells grown at 55 C contained a lower level of autolytic ability, produced cell walls which bound more Mg
2+
, and contained less peptide cross-bridging in its peptidoglycan layer than cells grown at 37 C.