bluuebunny/crossref_metadata_2025 huggingface dataset:
Intracellular, periodic structures in the gliding bacterium Myxococcus xanthus
Authors: Burchard A C , Burchard R P , Kloetzel J A
Published: January 2020

Electron microscopic observations of thin sections of Myxococcus xanthus vegetative cells revealed the presence of cytoplasmic bundles of 4- to 5-nm-diameter filaments running longtitudinally below the cell membrane and terminating in association with the envelope near one pole. Part of each bundle demonstrated a herringbone-like periodicity (approximately 12-nm spacing). This structure was observed in cells from shake cultures and in gliding cells fixed by several methods. It is proposed that the structure may be attached to the envelope near both poles in gliding cells and that the motive force for motility may be provided by its contraction and relaxation. In one of four nongliding mutants examined, the periodicity was indistinct or lacking. In this mutant another structure, comprised of linearly arrayed beads, was observed in association with the filamentous bundle. Another structure, characterized by major, transverse bands (approximately 34 nm apart), occurred in patches that may traverse the diameter of the wild-type cells in which the structure was observed.
Cell Wall and Morphological Changes Induced by Temperature Shift in
Bacillus subtilis
Cell Wall Mutants
Authors: Shiflett M. A. , Brooks David , Young F. E.
Published: January 2020

Bacillus subtilis
RUB1012 and RUB1013 have the following phenotype when grown at 45°C: no growth on tryptose blood agar base, growth as clumps of spheres in broth culture, a slow autolysis rate, and a low proportion of teichoic acid to peptidoglycan. Revertants of strain RUB1012 (RUB2032, RUB2012, and RUB2042) that could grow on tryptose blood agar base were isolated. Each revertant had a different proportion of teichoic acid to peptidoglycan. The nanomoles of phosphorus per milligram of cell wall at the nonpermissive temperature were 141, 160, 236, and 541 for strain RUB1012 and revertants RUB2032, 2012, and 2042, respectively, as compared with 1,100 for the parent strain. With most bacteriophage tested, plating efficiency was related to the amount of glucosylated teichoic acid. Scanning electron microscopy was used to study strain RUB2032 during a shift from growth at 30°C to growth at 45°C. The change from rod to sphere began with the thickening of the cylindrical portion of the cell. Caps of the cells appeared to be immune to the thickening process. During growth, the cells became progressively shorter and thicker, and cell separation was inhibited. When cells of strain RUB2032 were shifted from growth at 45°C to growth at 30°C, accumulation of an amorphous material on the outer surfaces of the cells preceded the change from sphere to rod morphology. Cells remained clumped, with rods appearing at the periphery of the clumps. Analysis by DNA-mediated transformation and PBS1-mediated transduction indicated that strains RUB1012 and RUB1013 have multiple mutations mapping in the same region as other cell wall mutations.
Direct selective procedure for isolating Neurospora mutants defective in nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase
Authors: Kinsey J A
Published: January 2020

A procedure has been developed for isolating nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase (am) mutants of Neurospora. Physiological, genetic, and enzymatic tests show that the new mutants are am alleles. Reconstruction tests and analysis of the new alleles show that the procedure yields a broad spectrum of lesions at the am locus. The isolation of am mutants by this technique appears to be related to the effect of am mutants on the control of the general permease.
Genetic Analysis of Components Involved in Vitamin B
12
Uptake in
Escherichia coli
Authors: Bassford Philip J. , Kadner Robert J.
Published: January 2020

The products of three genes are involved in cyanocobalamin (B
12
) uptake in
Escherichia coli. btuB
(formerly
bfe
), located at min 88 on the
Escherichia coli
linkage map, codes for a protein component of the outer membrane which serves as receptor for B
12
, the E colicins, and bacteriophage BF23. Four phenotypic classes of mutants varying in response to these agents were found to carry mutations that, based on complementation and reversion analyses, reside in the single
btuB
cistron. In one mutant class, ligand binding to the receptor appeared to be normal, but subsequent B
12
uptake was defective. The level of receptor and rate of uptake were responsive to
btuB
gene dosage. Previous studies showed that the
tonB
product was necessary for energy-dependent B
12
uptake but not for its binding. Other than those in
tonB
, no mutations that conferred insensitivity to group B colicins affected B
12
utilization. The requirement for the
btuB
and
tonB
products could be bypassed by elevated levels of B
12
(>1 μM) or by mutations compromising the integrity of the outer membrane as a permeability barrier. Utilization of elevated B
12
concentrations in strains lacking the
btuB-tonB
uptake system was dependent on the function of the
btuC
product. This gene was located at 37.7 min on the linkage map, with the order
pps-btuC-pheS
. Strains altered in
btuC
but with an intact
btuB-tonB
system were only slightly impaired in B
12
utilization, being defective in its accumulation. This defect was manifested as inability to retain B
12
, such that intracellular label was almost completely lost by exchange or efflux. It is proposed that
btuC
encodes a transport system for B
12
in the periplasm.
Donor Strains of the Soft-Rot Bacterium
Erwinia chrysanthemi
and Conjugational Transfer of the Pectolytic Capacity
Authors: Chatterjee Arun K. , Starr Mortimer P.
Published: January 2020

Donor strains of
Erwinia chrysanthemi
ICPB EC16, a member of the soft-rot (pectolytic) section of the enterobacterial genus
Erwinia
, were obtained by chromosomal integration of an F′
lac
+
plasmid originating from
Escherichia coli
. These stable donor strains, selected from an unstable F′
lac
+
heterogenote by repeated platings of single Lac
+
colonies on lactose minimal agar, do not segregate (as does the parent F′
lac
+
heterogenote) into Lac
−
or F
−
clones, in either the presence or absence of acridine orange. One representative donor strain (from the 12 that have been selected) has been examined in more detail; it can transfer
ade
+
,
gal
+
,
gtu
+
(utilization of galacturonate),
his
+
,
lac
+
,
leu
+
,
lys
+
,
mcu
+
(multiple carbohydrate utilization),
pat
+
(production of polygalacturonic acid
trans
-eliminase),
thr
+
, and
trp
+
in a polarized manner to appropriate recipient strains of
E. chrysanthemi
; the frequencies of
ade
+
,
leu
+
, and
thr
+
transfer were higher than those of the other markers tested to date. This donor strain transfers
lac
+
genes during a 6-h mating on membranes; most of the Lac
+
recombinants are donors of chromosomal markers. The kinetics of entry as well as the frequencies of transfer of chromosomal markers indicate that
thr
+
and
leu
+
enter the recipient as proximal markers and that
lac
+
enters as a distal marker. Analysis of the recombinants demonstrates close linkage between
thr
and
leu, ade
and
thr, his
and
pat
, and
his
and
trp
loci. The results suggest that the integration of F′
lac
+
into the chromosome of
E. chrysanthemi
has occurred at a region adjacent to the
leu-thr
loci, and that the chromosome is transferred in the following sequence: origin----
leu--thr--ade--lys--mcu--pat--his--trp--gal--gtu--lac
--F. Plant-tissue maceration occurs in Pat
+
recombinants and not in Pat
−
recombinants, even though both form another pectolytic enzyme, hydrolytic polygalacturonase. This genetic evidence supports the idea that the
E. chrysanthemi
polygalacturonic acid
trans
-eliminase plays an essential role in bringing about plant-tissue maceration.
Bacteriophage conversion of heat-labile enterotoxin in Escherichia coli
Authors: Takeda Y , Murphy J R
Published: January 2020

A temperate phage designated obeta1 (omicron beta) was mitomycin C induced and isolated from heat-labile enterotoxin (LT)-producing Escherichia coli E2631-C2. Phage obeta1 infected the nonlysogenic, nontoxigenic, mitomycin C-sensitive strain of E. coli K-12 (CSH38) and converted it to lysogeny and enterotoxigenicity. After the establishment of lysogeny, E. coli CSH38(obeta1) produced produced LT and phage particles at maximal levels following mitomycin C induction. The LT Tox+ character is carried by the temperate phage obeta1.
R plasmic Rtsl-mediated production of extracellular deoxyribonuclease in Escherichia coli
Authors: Matsumoto H , Kamio Y , Kobayashi R , Terawaki Y
Published: January 2020

Escherichia coli strains harboring Rtsl were found to excrete extracellular deoxyribonuclease. The DNase activity was greater in cells with pTW2, a mutant from Rtsl.
Enhanced sensitivity to the photodynamic effect of 3,4-benzpyrene in ethylenediaminetetraacetate-treated Escherichia coli
Authors: Coratza G , Molina A M
Published: January 2020

Ethylenediaminetetraacetate treatment of Escherichia coli B enhanced cell sensitivity to the lethal effect of the photodynamic action of 3,4-benzpyrene. The alteration of the shape of the survival curve suggests that such photodynamic action may be modified by membrane barriers to the drug.
F- mating materials able to generate a mating signal in mating with HfrH dnaB(Ts) cells
Authors: Ou J T , Reim R L
Published: January 2020

The purified outer membrane from F- (W1-3) cells was shown to inhibit mating effectively, but the purified cytoplasmic (inner) membrane did not. These membranes, heat-treated minicells, and ultraviolet-irradiated minicells were examined for their ability to generate a mating signal at 43 degrees C in mating with HfrH dnaB(Ts) cells. The outer and inner membranes and heat-treated minicells all failed to stimulate incorporation of radioactive thymine; only ultraviolet-irradiated minicells retained the ability to generate a mating signal for the donor to initiate transfer replication.
Properties of the halophilic nuclease of a moderate halophile, Micrococcus varians subsp. halophilus
Authors: Kamekura M , Onishi H
Published: January 2020

The halophilic nuclease of Micrococcus varians ATCC 21971 hydrolyzed thymidine 5'-monophospho-p-nitrophenyl ester at a rate that increased with the NaCl concentration up to saturation. The nuclease attacked RNA and DNA exonucleolytically and processively, producing 5'-mononucleotides. The molecular weight of the enzyme as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was 99,000, approximately the same as that previously determined for the native enzyme. Examination of amino acid composition showed that acidic amino acids were in high excess over basic amino acids.
Sequence of b cytochromes relative to ubiquinone in the electron transport chain of Escherichia coli
Authors: Downie J A , Cox G B
Published: January 2020

A ubiquinone-deficient mutant, carrying mutations in two genes affecting ubiquinone biosynthesis, has been used, in comparison with a normal strain, to determine the sequence of some of the components of the electron transport chain of Escherichia coli. The amounts of cytochromes reduced during aerobic steady-state conditions were estimated by comparing low-temperature difference spectra of normal or ubiquinone-deficient membranes with either D-lactate or reduced nicotinamide adenine dinucleotide as substrate. From the amounts of cytochromes reduced it was concluded that ubiquinone functions at two sites, one site being between the dehydrogenases and cytochromes and the second site being after cytochromes b562 and b556 but before cytochromes b558, d, and o. The scheme proposed is discussed in relation to the Mitchell protonmotive ubiquinone cycle.
Isolation of specialized transducing bacteriophages carrying the structural genes of the hexuronate system in Escherichia coli K-12: exu region
Authors: Mata M , Delstanche M , Robert-Baudouy J
Published: January 2020

In Escherichia coli HfrH 58, isolated by Shimada et al., a heat-inducible phage has been integrated in a secondary attachment site. We have characterized tha nature of the lambda integration. The exuR regulatory gene is inactivated by prophage integration. Genetic and biochemical analysis indicated a gene order: uxaA-uxaC-exuT-(exuR')-lambdaNRAJ (exuR''). By induction of HfrH 58, one class of deletions extending into the exu region was obtained. Analysis of these deletions confirms the exu region topography and the regulatory mechanism of the hexuronate system previously described. It has been possible to regenerate a functional exuR gene by prophage exision. Various lambda transducing particles plaque-forming and defective transducing phages carrying the left part or the right part of the exu region, have been derived from the secondary site lysogen HfrH 58. A phage carrying the entire exuR region was constructed by a cross between these two types of phage. The construction and characterization of these exu transducing phages are presented.
Production of giant cells of Escherichia coli
Authors: Long W S , Slayman C L , Low K B
Published: January 2020

Giant cells, with volumes up to 500-fold those of normal cells, have been produced by both genetic and pharmacological means in Escherichia coli K-12. In the genetic approach, an envB or mon mutation (conferring rounded or irregular morphology) was combined with a lon mutation (block of septation after irradiation). UV irradiation and subsequent incubation for 2 to 5 h in a rich medium supplemented with 1% sodium chloride led t; production of polymorphic giant cells. In the pharmacological approach, incubation of several different strains of E. coli K-12 with the drug 6-amidinopenicillanic acid (FL1060) in the same rich medium gave rise to a homogeneous population of smoothly rounded giant cells.
Protonmotive force and motility of Bacillus subtilis
Authors: Shioi J I , Imae Y , Oosawa F
Published: January 2020

Motility of Bacillus subtilis was inhibited within a few minutes by a combination of valinomycin and a high concentration of potassium ions in the medium at neutral pH. Motility was restored by lowering the concentration of valinomycin or potassium ions. The valinomycin concentration necessary for motility inhibition was determined at various concentrations of potassium ions and various pH's. At pH 7.5, valinomycin of any concentration did not inhibit the motility, when the potassium ion concentration was lower than 9 mM. In the presence of 230 mM potassium ion, the motility inhibition by valinomycin was not detected at pH lower than 6.1. These results are easily explained by the idea that the motility of B. subtilis is supported by the electrochemical potential difference of the proton across the membrane, or the protonmotive force. The electrochemical potential difference necessary for motility was estimated to be about -90 mV.
Arginine metabolism in Saccharomyces cerevisiae: subcellular localization of the enzymes
Authors: Jauniaux J C , Urrestarazu L A , Wiame J M
Published: January 2020

Subcellular localization of enzymes of arginine metabolism in Saccharomyces cerevisiae was studied by partial fractionation and stepwise homogenization of spheroplast lysates. These enzymes could clearly be divided into two groups. The first group comprised the five enzymes of the acetylated compound cycle, i.e., acetylglutamate synthase, acetylglutamate kinase, acetylglutamyl-phosphate reductase, acetylornithine aminotransferase, and acetylornithine-glutamate acetyltransferase. These enzymes were exclusively particulate. Comparison with citrate synthase and cytochrome oxidase, and results from isopycnic gradient analysis, suggested that these enzymes were associated with the mitochondria. By contrast, enzymatic activities going from ornithine to arginine, i.e., arginine pathway-specific carbamoylphosphate synthetase, ornithine carbamoyltransferase, argininosuccinate synthetase, and argininosuccinate lyase, and the two first catabolic enzymes, arginase and ornithine aminotransferase, were in the "soluble" fraction of the cell.
Interspecies transformation in Bacillus: sequence heterology as the major barrier
Authors: Harris-Warrick R M , Lederberg J
Published: January 2020

The relative contribution of DNA restriction and of sequence heterology as barriers to interspecies transfer of DNA was studied in the heterologous transformation of Bacillus subtilis recipients by DNA was studied in the heterologous transformation of Bacillus subtilis recipients by DNA isolated from B. globigii. Transformants were obtained at very low frequencies in the evolutionarily nonconserved aromatic region; high cotransfer of linked markers was observed. New mutations were introduced into the B. globigii intergenote sequence in the resulting hybrids; these markers could be transformed with high efficiency by both B. globigii and B. subtilis DNA, representing a 10(5)-fold increase in heterologous transforming efficiency. A restriction activity in B. globigii crude extracts inactivated the biological activity of B. subtilis and hybrid DNA but not B. globigii DNA in vitro, demonstrating different sites for restriction and modification between these species. In vivo, however, B. globigii and hybrid DNA transformed the B. globigii sequence in a hybrid recipient with the same efficiency. These results show that sequence heterology is the major barrier to interspecies transformation and that, in this system, enzymatic restriction does not prevent interspecies transformation.
Divalent cation transport systems of Rhodopseudomonas capsulata
Authors: Jasper P , Silver S
Published: January 2020

Separate divalent cation transport systems for energy-dependent uptake of Mg2+ and Mn2+ were found both with aerobically and heterotrophically grown and with photosynthetically grown cells of Rhodopseudomonas capsulata. The maximum rate of Mg2+ uptake differed between photosynthetic and aerobic cells, while the Km for the Mg2+ transport system was constant. Photosynthetic midlog-phase cells exhibited Km's for uptake of about 55 micrometer Mg2+ and 0.5 micrometer Mn2+. The Vmax's also differed between the two systems: 0.6 to 1.8 mumol/min per g (dry weight) of cells for Mg2+, but only 0.020 mumol/min per g for Mn2+, making the distinction between a "macro-requirement" system and a system functioning at trace nutrient levels. Calcium was not normally taken up by intact cells of R. capsulata. However, chromatophore membranes isolated from photosynthetic cells took up Ca2+ by an energy-dependent process.
Involvement of the product of the glnF gene in the autogenous regulation of glutamine synthetase formation in Klebsiella aerogenes
Authors: Gaillardin C M , Magasanik B
Published: January 2020

Mutations in a site, glnF, linked by P1-mediated transduction of argG on the chromosome of Klebsiella aerogenes, result in a requirement for glutamine. Mutants in this gene have in all media a level of glutamine synthetase (GS) corresponding to the level found in the wild-type strain grown in the medium producing the strongest repression of GS. The adenylylation and deadenylylation of GS in glnF mutants is normal. The glutamine requirement of glnF mutants could be suppressed by mutations in the structural gene for GS, glnA. These mutations result in altered regulation of GS synthesis, regardless of the presence or absence of the glnF mutation (GlnR phenotype). In GlnR mutants the GS level is higher than in the wild-type strain when the cells are cultured in strongly repressing medium, but lower than in the wild-type strain when cells are cultured in a derepressing medium. Heterozygous merodiploids carrying a normal glnA gene as well as a glnA gene responsible for the GlnR phenotype behave in every respect like merodiploids carrying two normal glnA genes. These results confirm autogenous regulation of GS synthesis and indicate that GS is both a repressor and an activator of GS synthesis. The mutation in glnA responsible for the GLnR phenotype has apparently resulted in the formation of a GS that is incompetent both as repressor and as activator of GS synthesis. According to this hypothesis, the product of the glnF gene is necessary for activation of the glnA gene by GS.
Translation of the leader region of the Escherichia coli tryptophan operon
Authors: Miozzari G F , Yanofsky C
Published: January 2020

When the trp operon of Escherichia coli contains either of two deletions that fuse the initial portion of the leader region to the distal segments of the trpE gene, novel fusion polypeptides are produced. The new polypeptides are synthesized efficiently both in vivo and in vitro, and their synthesis is subject to repression by trp repressor. Fingerprint analyses of tryptic and chymotryptic digests of the new polypeptides show that both contain trpE polypeptide sequences and, despite their different sizes, share the same N-terminal sequence. Our results suggest that synthesis of the new polypeptides is initiated at the AUG-centered ribosome-binding site in the leader region and proceeds in phase to the region coding for the C-terminal end of the trpE polypeptide.
Effect of cell length on gliding motility of Flexibacter
Authors: Costenbader C J , Burchard R P
Published: January 2020

Short Flexibacter FS-1 cells, generated during logarithmic growth in glucose-salts medium or by filament fragmentation during the transition from log to stationary phase in rich medium, are unable to glide. Motility returns when cells elongate. This strain also dissociates stable, short, nongliding variants.
Identification and synthesis of acyl-phosphatidylglycerol in Acinetobacter sp. HO1-N
Authors: Makula R A , Torregrossa R E , Isle H B
Published: January 2020

A minor phospholipid from Acinetobacter sp. HO1-N was identified as acyl-phosphatidylglycerol. Acyl-phosphatidylglycerol synthesis by outer-membrane preparations appeared to be a result of phospholipase A activity.
Purification and characterization of extracellular soluble and membrane-bound insoluble alkaline phosphatases possessing phosphodiesterase activities in Bacillus subtilis
Authors: Yamane K , Maruo B
Published: January 2020

A membrane-bound insoluble alkaline phosphatase (APase) and an extracellular soluble APase were purified, respectively, from a membrane preparation of Bacillus subtilis 6160-BC6, which carries a mutation to produce APase constitutively, and from a culture fluid of a mutant strain. RAN 1, isolated from strain 6160-BC6, which produces an extracellular soluble APase. The two preparations were homogeneous, as judged by sodium dodecyl sulfate discontinuous gel electrophoresis and by gel electrophoreses in the presence of 8 M urea at pH 9.3 and 4.3. RAN 1 APase was crystallized. Both preparations possessed phosphatase and phosphodiesterase activities, and their pH optima were both at 9.5. They were competitively inhibited by phosphate or arsenate and were activated by the addition of Ca2+ but not by Zn2+. The APase and alkaline phosphodiesterase activities seemed to be contained in the same protein molecule. The molecular weight of 6160-BC6 APase was estimated to be 46,000 +/- 1,000, and that of RAN 1 APase was estimated to be 45,000 +/- 1,000. The largest difference between the 6160-BC6 and RAN 1 APase's was in solubility in low-ionic-strength solutions. Present results suggest that each enzyme is composed of a single polypeptide chain and that 6160-BC6 APase aggregates in solutions of low ionic strength.
Structure-Function Relationships in the Arginine Pathway Carbamoylphosphate Synthase of
Saccharomyces cerevisiae
Authors: Piérard André , Schröter Brigitte
Published: January 2020

The arginine pathway carbamoylphosphate synthase (CPSase A) from
Saccharomyces cerevisiae
was shown to be highly unstable and could not be substantially purified. In spite of this instability, a number of important properties of this enzyme were determined with crude preparations. A molecular weight of 140,000 (7.9S) was estimated for the native enzyme by sucrose gradient centrifugation; a significantly higher value, 175,000, was obtained by gel filtration on Sephadex. The enzyme is an aggregate consisting of two protein components, coded for by the unlinked genes
cpaI
and
cpaII
. These components were separated by diethylaminoethyl-cellulose chromatography. Their molecular weights, estimated by Sephadex gel filtration, were 36,000 and 130,000. The large component catalyzed the synthesis of carbamoylphosphate from ammonia. The small component was required in addition to the large one for the physiologically functional glutamine-dependent activity. Apparent Michaelis constants at pH 7.5 of 1.25 mM for glutamine and 75 mM for NH
4
Cl were measured with the native enzyme. The use of various glutamine analogs, including 2-amino-4-oxo-5-chloropentanoic acid, indicated that binding of glutamine to a site located on the small component was followed by transfer of its amide nitrogen to the ammonia site on the heavy component. This ammonia site was able to function independently of the utilization of glutamine. However, binding of glutamine was conjectured to cause a conformational change in the heavy component that greatly increased the rate of synthesis of carbamoylphosphate from ammonia. Glutamine, which was also shown to stabilize the aggregation of the two components, appeared to be a major effector of the catalytic and structural properties of CPSase A. In view of these observations, the CPSase A of yeast appears to share a number of structural and catalytic properties with the
Escherichia coli
enzyme. Obviously, the unlinked
cpaI
and
cpaII
genes of yeast are homologous to the adjacent
carA
and
carB
genes that code for the two subunits of the bacterial enzyme.
Identification of a biochemically unique DNA-membrane interaction involving the Escherichia coli origin of replication
Authors: Craine B L , Rupert C S
Published: January 2020

DNA-membrane complexes have been obtained from Escherichia coli by using a freeze-thaw lysis procedure that avoids lysozyme and detergents. Complexes made in this manner and containing DNA near the origin of replication are uniquely sensitive to ionic strength, Pronase, and trypsin. There is approximately one such complex per chromosomal origin. The sensitivities suggest that origin-specific binding is mediated by a protein. By using these unique characteristics to distinguish origin-specific complexes from the majority of DNA-membrane binding sites, it was found that the origin-specific binding persists after termination of chromosomal replication.
Biochemical and genetic properties of site-specific restriction endonucleases in Bacillus globigii
Authors: Duncan C H , Wilson G A , Young F E
Published: January 2020

Bacillus globigii contains two site-specific endonucleases, BPGLI AND BglI. A rapid technique for selection of mutants deficient in each of these enzymes was developed using sensitivity to infection by bacteriophage SP50 as an indication of the levels of enzyme. Mutants defective in BglI, BglII, and both BglI and BglII retained the wild-type modification phenotype. Genetic and biochemical studies have established that these enzymes are involved in restriction in vivo. Simplified purification procedures for BglI and BglII using these mutants are described.
Cyclic AMP-dependent synthesis of fimbriae in Salmonella typhimurium: effects of cya and pts mutations
Authors: Saier M H , Schmidt M R , Leibowitz M
Published: January 2020

Synthesis of bacterial fimbriae (group 1, subtype 1) was shown to be dependent on cyclic AMP and was subject to catabolite repression by many carbohydrates. Mutations in the genes coding for the energy-coupling protein constituents of the phosphoenolpyruvate:sugar phosphotransferase system prevented repression of fimbrial production by the sugar substrates of this enzyme system.
Regulation of macromolecular synthesis during hyphal germ tube emergence from Mucor racemosus sporangiospores
Authors: Orlowski M , Sypherd P S
Published: January 2020

Protein and RNA syntheses were examined during hyphal germ tube emergence from sporangiospores of a dimorphic phycomycete, Mucor racemosus. Both classes of macromolecules were synthesized immediately upon introduction of the dormant sporangiospores into nutrient medium. The specific rates of synthesis of both protein and RNA accelerated during initial germ tube emergence and reached a maximum when the emergence of new germ tubes ended. The specific rates of synthesis later decreased during further hyphal elongation. The distribution of ribosomes between active polysomes and monosomes and inactive subunits was determined by sucrose density gradient centrifugation, and the rate of amino acid addition to nascent polypeptide chains was calculated throughout the developmental sequence. The results showed that both the percentage of ribosomes active in protein synthesis and the velocity of ribosome movement along the mRNA were continuously adjusted throughout hyphal germ tube development. The free intracellular amino acid pools were measured throughout development. Alanine, glutamate, and aspartate were present at very high concentrations in the dormant spores but were rapidly depleted during hyphal germ tube emergence. The results of these studies are discussed in relation to hyphal germ tube development from yeast cells of Mucor and dormant spores of other fungal species.
Ribitol and D-arabitol catabolism in Escherichia coli
Authors: Scangos G A , Reiner A M
Published: January 2020

In Escherichia coli C, the catabolism of the pentitols ribitol and D-arabitol proceeds through separate, inducible operons, each consisting of a dehydrogenase and a kinase. The ribitol operon is induced in response to ribulose, and the D-arabitol operon is induced in response to D-arabitol. Each operon is under negative control. The genes of the ribitol and D-arabitol operons are very closely linked and lie in a mirror image arrangement, rtlB-rtlA-rtlC-atlC-atlA-atlB, between metG and his on the E. coli chromosome.
Effects of selected inhibitors on electron transport in Neisseria gonorrhoeae
Authors: Kenimer E A , Lapp D F
Published: January 2020

The electron transport system of Neisseria gonorrhoeae was partially characterized by using spectrophotometric, spectroscopic, and oxygen consumption measurements. The effects of selected electron transport inhibitors (amytal, rotenone, 2-heptyl-4-hydroxyquinoline, antimycin A1, and potassium cyanide [KCN]) on electron transfer in whole-cell and sonically treated whole-cell preparations of N. gonorrhoeae were examined. The oxidation of reduced nicotinamide adenine dinucleotide, measured as a decrease in absorbance at 340 nm, was inhibited by each of the compounds tested. Oxygen consumption stimulated by reduced nicotinamide adenine dinucleotide was also inhibited, whereas oxygen uptake stimulated by succinate and malate was inhibited by KCN alone, suggesting the presence of a KCN-sensitive terminal oxidase. Room temperature optical difference spectra indicate an operational electron bypass around the amytal-rotenone-binding site. Difference spectra in the presence of 2-heptyl-4-hydroxyquinoline suggest a possible site of interaction of this compound at the substrate side of cytochrome b. Reduced-minus-oxidized spectra of ascorbate-tetramethyl-p-phenylenediamine suggest the participation of b-, a-, and d-type cytochromes in terminal oxidase activity. Hence, N. gonorrhoeae appears to have an electron transport chain containing cytochrome c, two b-type cytochromes (one of which has an oxidase function), and possibly a- and d-type cytochromes. An abbreviated chain exists through which succinate and malate can be oxidized directly by a KCN-sensitive component.
Glutamate-induced uptake of proline by Streptomyces antibioticus
Authors: May W S , Formica J V
Published: January 2020

Streptomyces antibioticus possesses an energy-dependent, carrier mediated transport system for the uptake of L-glutamate and L-proline. Amino acid transport was found to have a temperature optimum of 35 degrees C and a pH optimum from 7.0 to 8.0 for glutamate and 6.5 to 7.5 for proline uptake. Uptake did not depend upon Mg2+, Ca2+, Zn2+, Na+, or Fe2+ ions. Reversible p-hydroxymercuribenzoate inhibition of uptake indicated the involvement of an active sulfhydryl group. L-Glutamate uptake was mediated by a glutamate-inducible, nonspecific transport system, which was extremely stable and was not subject to substrate inhibition by L-proline. On the other hand, L-proline transport was mediated by at least two systems. The L-glutamate-inducible nonspecific system can account for uptake of proline by the mycelium grown in glutamate. In addition, a proline-specific, constitutive transport system was found to be present in the mycelium grown in organic and inorganic nitrogen sources other than L-glutamate. Shift experiments revealed that proline transport is not as stable as glutamate transport when the glutamate-inducible nonspecific system is utilized.
Regulation of glutamine synthetase formation in Escherichia coli: characterization of mutants lacking the uridylyltransferase
Authors: Bloom F R , Levin M S , Foor F , Tyler B
Published: January 2020

A lambda phage (lambdaNK55) carrying the translocatable element Tn10, conferring tetracycline resistance (Tetr), has been utilized to isolate glutamine auxotrophs of Escherichia coli K-12. Such strains lack uridylyltransferase as a result of an insertion of the TN10 element in the glnD gene. The glnD::Tn10 insertion has been mapped at min 4 on the E. coli chromosome and 98% contransducible by phage P1 with dapD. A lambda transducing phage carrying the glnD gene has been identified. A glnD::Tn10 strain synthesizes highly adenylylated glutamine synthetase under all conditions of growth and fails to accumulate high levels of glutamine synthetase in response to nitrogen limitation. However, this strain, under nitrogen-limiting conditions, allows synthesis of 10 to 20 milliunits of biosynthetically active glutamine synthetase per mg of protein, which is sufficient to allow slow growth in the absence of glutamine. The GlnD phenotype in E. coli can be suppressed by the presence of mutations which increase the quantity of biosynthetically active glutamine synthetase.
Stable denaturation of chromosomal DNA from Saccharomyces cerevisiae during meiosis
Authors: Klein H L , Byers B
Published: January 2020

Partial denaturation of Saccharomyces cerevisiae chromosomal DNA was found to occur spontaneously during meiosis. Short regions of strand separation (300 base pairs long) were seen in DNA molecules prepared for electron microscopy by the aqueous spreading technique. These regions were clustered along the DNA. The time course of their appearance indicated that the denatured regions were present during the periods of premeiotic DNA replication and recombination. A similar pattern of denaturation was also detected in the DNA from vegetatively grown cells of a conditional cdc8 mutant, which is defective in DNA replication.
Tetrahydrofolate enzyme levels in Acetobacterium woodii and their implication in the synthesis of acetate from CO2
Authors: Tanner R S , Wolfe R S , Ljungdahl L G
Published: January 2020

Acetate synthesis from CO2 by Acetobacterium woodii may occur as in homoacetate-fermenting clostridia, as indicated by high levels of enzymes of the tetrahydrofolate pathway and by pyruvate-dependent formation of acetate from methyl-B12 and methyltetrahydrofolate.
Lipoprotein from Proteus mirabilis
Authors: Katz E , Loring D , Inouye S , Inouye M
Published: January 2020

The biosynthesis of a Proteus mirabilis outer membrane protein of molecular weight of approximately 7,000 was found to be relatively resistant to puromycin and rifampin, as is the case for the Escherichia coli liporotein. Furthermore, the existence of the lipoprotein in P. mirabilis was indicated by a comparison of the amino acid compositions of the purified free and bound forms of this protein with those of the E. coli free and bound lipoproteins.
Carbodiimide-resistant mutant of Escherichia coli: suppression of resistance to dicyclohexylcarbodiimide by growth on glucose or glycerol
Authors: Fillingame R H , Wopat A E
Published: January 2020

We have previously reported on the isolation of a mutant strain of Escherichia coli, RF-7, that has a dicyclohexylcarbodiimide (DCCD)-resistant, membrane-associated adenosine triphosphatase (ATPase) activity (R. H. Fillingame, J. Bacteriol. 124:870--883, 1975). We report here that the DCCD resistance of the ATPase of this mutant varies significantly, depending upon the carbon source used for growth. When strain RF-7 was grown aerobically on either glycerol or glucose or anaerobically on glucose rather than on a combination of succinate, acetate, and malate, ATPase activity was more sensitive to inhibition by DCCD because the carbodiimide-reactive proteolipid reacted more readily with DCCD.
Regulation of initial rate of induction of nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase during the cell cycle of synchronous Chlorella
Authors: Turner K J , Gronostajski R M , Schmidt R R
Published: January 2020

When synchronous cells of the eucaryotic microorganism Chlorella sorokiniana growing in nitrate medium were challenged to synthesize an ammonium-inducible nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase (NADP-GDH) at frequent intervals during the cell cycle the initial rate of induction (i.e., enzyme potential) of this enzyme increased in an approximately linear manner until the period of DNA replication (i.e., S phase). During the S phase, NADP-GDH potential exhibited a positive rate change proportional to the step increase in DNA level. The timing of this rate change was insensitive to large changes in cellular growth rate. This rate change could be blocked within the first cell cycle by specific inhibition of DNA replication with 2'-deoxyadenosine. The approximately linear increase in NADP-GDH potential and also of total cellular protein observed before and after the S phase is proposed to be a result of the increasing photosynthetic capacity of the cell during the cell cycle.
Association of long surface appendages with adherence-related functions of the gram-positive species Actinomyces naeslundii
Authors: Ellen R P , Walker D L , Chan K H
Published: January 2020

Electron microscopy of new isolates of gram-positive Actinomyces naeslundii demonstrated long, fragile appendages. Removal of the appendages impaired attachment to epithelial cells and reaggregation, thus implicating them in attachment-related functions.
Polyamines of Anacystis nidulans and metabolism of exogenous spermidine and spermine
Authors: Ramakrishna S , Guarino L , Cohen S S
Published: January 2020

Several biochemical parameters, including that of polyamine content, accompanying the growth of the cyanobacterium Anacystis nidulans were studied. At all stages of growth under autotrophic conditions, the organisms were found to be rich in spermidine and lacking in spermine, as is typical of procaryotic organisms. The cells were quite low in putrescine, and no unusual polyamine was observed to be present as a major component. Conjugated polyamines were not detected in the cultures. At maximal culture density, the levels of spermidine, DNA, RNA, protein, and chlorophyll were also maximal. Shortly after the inception of the stationary phase, the spermidine content of the cells was the first parameter observed to decrease in cultures which were shortly to become yellow. Spermidine lost from the cells was not recovered in the medium in a free or conjugated form. This indication of degradation of spermidine was studied by the addition of polyamines to growing cultures. Exogenous spermidine and spermine were found to be metabolized rapidly by the organisms, of which diaminopropane was one product. Putrescine was found to be markedly toxic, whereas spermidine, some other triamines, and spermine were much less toxic.
Variations among glyV-derived glycine tRNA suppressors of glutamic acid codons
Authors: Murgola E J , Prather N E , Hadley K H
Published: January 2020

Glutamic acid codon suppressors in 18 isogenic strains of Escherichia coli have been further characterized as to map location, dominance, growth rates in various media, suppression of the GAG codon, and tRNA profiles after reversed-phase column chromatography. In general the evidence supports the conclusion that all of these suppressors are due to mutations in glyV55, the gene for a GGA/G-reading mutant form of glyV tRNA, and that they represent several different classes that may correspond to at least as many different nucleotide changes. Furthermore, 17 of the 18 suppressors can coexist in a haploid genome with a glyT suppressor that is devoid of GGA-reading ability. This result indicates the retention by those glyV suppressors of some ability to respond to GGA as well as the acquisition of the ability to read GAA, and suggests the possibility of "wobble" in the middle position of the anticodons of those tRNA's.
Dependence of Escherichia coli hyperbaric oxygen toxicity on the lipid acyl chain composition
Authors: Harley J B , Santangelo G M , Rasmussen H , Goldfine H
Published: January 2020

This study examines certain membrane-related aspects of oxygen poisoning in Escherichia coli K1060 (fabB fadE lacI) and its parent strain, K-12 Ymel. Cells were grown to exponential or stationary phase in a minimal medium and exposed to air plus 300 lb/in2 of O2 as a suspension in minimal salts. After an initial lag, both strains lost viability with apparent first-order kinetics. Hypebaric oxygen was more toxic to cells harvested during the exponential phase of growth than to cells harvested from the stationary phase of growth for both strains K-12 Ymel and K1060. Control suspensions exposed to air plus 300 lb/in2 of N2 did not lose viability during a 96-h exposure. The sensitivity of the unsaturated fatty acid auxotroph, strain K1060, to hyperbaric oxygen increased as the degree of unsaturation of the fatty acid supplement increased. Cells grown with a cyclopropane fatty acid (9,10=methylenoctadecanoate) were the most resistant; cells grown with a monounsaturated fatty acid (oleate) were intermediate; and those grown with polyunsaturated fatty acids (linoleate and linolenate) were most sensitive to hyperbaric oxygen. The parent strain, K-12 Ymel, lost viability in hyperbaric oxygen most similarly to strain K1060 supplemented with oleate. To determine the relative effect of hyperbaric oxygen on the survival of E. coli with saturated membranes, substrains of K1060 were selected for growth on 12-methyltetrade-canoate or on 9 or 10-monobromostearate. Substrains grown with a saturated fatty acid supplement were equally or more sensitive to hyperbaric oxygen than when the same substrains were grown with a cyclopropane fatty acid supplement. The lipid acyl chain composition was determined in E. coli K1060 before and after exposure to hyperbaric oxygen or hyperbaric nitrogen. The proportion of nonsaturated acyl chain lipid of either the oleate- or the 9,10-methyleneoctade-canoate-supplemented K1060 remained unchanged after hyperbaric gas exposure. In strain K1060 supplemented with linoleate and grown to stationary phase, however, the relative unsaturated acyl chain content after hyperbaric exposure decreased in both gases. This finding prompted an investigation of the role of lipid oxidation in hyperbaric oxygen toxicity. Assays of potential lipid oxidation products were performed with linoleate-grown cells. The lipid hydroperoxide and peroxide content of the lipid extract increased by 6.9 times after 48 h of air plus 300 lb/in2 of O2; malondialdehyde and fluorescent complex lipid oxidation products showed much smaller or no changes. Lipid extracts from hyperbaric oxygen-exposed cells were not toxic to viable E. coli K1060, nor did they increase the rate of loss of viability in cells simultaneously exposed to hyperbaric oxygen. Linoleic acid hydroperoxide at 1.0 mM had no effect on the viability of E. coli K-12 Ymel and only marginally decreased the viability of E. coli K1060 supplemented with linoleate. We conclude that the kinetics of oxygen toxicity in E...
Hyper-recombination in Escherichia coli K-12 mutants constitutive for protein X synthesis
Authors: Lloyd R G
Published: January 2020

Genetic recombination was studied in Escherichia coli F- strains in which synthesis of the recA gene product protein X is increased due to mutation in either recA (tif-1) or lexA (spr). When a single donor marker was selected, the recombination proficiency of these strains was not significantly altered in Hfr crosses. However, linkage of unselected, proximal Hfr markers was found to be much reduced among the progeny tested, and more of the progeny showed evidence of multiple exchanges between donor and recipient DNA. These effects were much more apparent when the recipient carried both tif-1 and spr mutations, but in this case recombination proficiency was reduced compared with those strains carrying either mutation alone, particularly in crosses with Hfr Cavalli. A lexA mutation was found to suppress the effect of tif-1 on the recombinant genotype.
Effect of ammonium ion concentration and osmotic pressure on growth of Ureaplasma urealyticum (T-strain mycoplasma)
Authors: Sayed I A , Kenny G E
Published: January 2020

The effect of ammonium ion concentration and osmotic pressure on growth of Ureaplasma urealyticum type VIII was determined by using a well-buffered broth medium containing 10 mM urea. The addition of NH4Cl to the medium at concentrations up to 10 mM did not affect growth; however, addition of larger quantities progressively decreased both the specific growth rate (mu) and the maximum yield of the culture, with concentrations of 80 mM completely inhibiting growth. Addition of either 150 mM KCl or NaCl to the medium did not inhibit growth, indicating that the growth-inhibitory effect was specific to NH4+ and was neither a result of increased Cl- concentration nor increased osmotic pressure. Concentrations of NH4Cl as high as 100 mM did not affect growth of either Acholeplasma laidlawii or Mycoplasma hominis. U. urealyticum was more sensitive to osmotic pressure: osmotic pressures of 710 to 780 mosmol/kg (with KCl, NaCl, or sucrose) resulted in both a substantially lower growth rate and a 5- to 10-fold lower peak yield of organisms. Both A laidlawii and M. hominis were less sensitive to increased osmotic pressure.
Bacillus subtilis 168 genetic transformation mediated by outgrowing spores: necessity for cell contact
Authors: Orrego C , Arnaud M , Halvorsen H O
Published: January 2020

Transforming activity released in sequential genetic order during the first synchronous cycle of DNA replication during outgrowth of spores of Bacillus subtilis 168 was investigated. A transformation assay was used consisting of outgrowing spores as DNA donors and multiply marked competent cells as recipients. DNA synthesis inhibitors known to stop DNA release were used during and subsequent to DNA transfer to recipient cells. The released DNA sedimented with the outgrowing cells after low-speed centrifugation, and it was discovered that markers released both early and late were resistant to up to 500 microgram of deoxyribonuclease per ml under conditions in which the transforming capacity of purified DNA was eliminated by 5 microgram of the nuclease per ml. Inaccessibility to deoxyribonuclease was increased and maintained during the transformation event while detergents and proteolytic attack did not expose the released chromosome to nuclease action. The results indicate that tight physical contact between outgrowing spores and competent cells is required for transformation in this system.