bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation of Escherichia coli mutants with an adenosine triphosphatase insensitive to aurovertin
Authors: Satre M , Klein G , Vignais P V
Published: January 2020

Energy-transducing adenosine triphosphatase (ATPase) from Escherichia coli is inhibited by aurovertin. Aurovertin-resistant mutants were generated by nitrosoguanidine mutagenesis of E. coli AN180, whose growth on a nonfermentable carbon source was blocked by aurovertin. The ATPase activity of cell extracts from 15 different mutants (designated MA1, MA2, MA3, etc.) was found to be at least 20 times less sensitive to aurovertin than that from the parent strain. The aurovertin-resistant mutants did not show cross-resistance towards a number of ATPase inhibitors including azide, dicyclohexylcarbodiimide, quercetin, 7-chloro-4-nitrobenzofurazan, and N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline. Aurovertin inhibited the energization brought about by addition of ATP to E. coli AN180 membrane vesicles; it was without effect on MA1 and MA2 membrane vesicles energized by ATP. The mutation in MA1, like other mutations of the ATPase complex, maps in the unc region of the bacterial chromosome.
Enolase from spores and cells of Bacillus megaterium: two-step purification of the enzyme and some of its properties
Authors: Singh R P , Setlow P
Published: January 2020

A simple two-step procedure for purification of enolase from germinated spores or vegetative cells of Bacillus megaterium is described. The procedure resulted in a 1,200-fold purification with production of homogeneous enzyme in approximately 75% yield; the enzymes from spores and cells seemed identical. The molecular weight of the native enzyme was 335,000, with a subunit molecular weight of 42,000. The enzyme required Mg2+ and was inhibited by ethylenediaminetetraacetic acid and fluoride ions. The Michaelis constants for 2-phosphoglyceric acid and Mg2+ were 7.1 X 10(-4) and 4.7 X 10(-4) M, respectively.
Metabolism of Cyclohexane Carboxylic Acid by
Alcaligenes
Strain W1
Authors: Taylor David G. , Trudgill Peter W.
Published: January 2020

Thirty-three microorganisms capable of growth with cyclohexane carboxylate as the sole source of carbon were isolated from mud, water, and soil samples from the Aberystwyth area. Preliminary screening and whole-cell oxidation studies suggested that, with one exception, all of the strains metabolized the growth substrate by beta-oxidation of the coenzyme A ester. This single distinctive strain, able to oxidize rapidly
trans
-4-hydroxycyclohexane carboxylate, 4-ketocyclohexane carboxylate,
p
-hydroxybenzoate, and protocatechuate when grown with cyclohexane carboxylate, was classified as a strain of
Alcaligenes
and given the number W1. Enzymes capable of converting cyclohexane carboxylate to
p
-hydroxybenzoate were induced by growth with the alicyclic acid and included the first unambiguous specimen of a cyclohexane carboxylate hydroxylase. Because it is a very fragile protein, attempts to stabilize the cyclohexane carboxylate hydroxylase so that a purification procedure could be developed have consistently failed. In limited studies with crude cell extracts, we found that hydroxylation occurred at the 4 position, probably yielding the
trans
isomer of 4-hydroxycyclohexane carboxylate. Simultaneous measurement of oxygen consumption and reduced nicotinamide adenine dinucleotide oxidation, coupled with an assessment of reactant stoichiometry, showed the enzyme to be a mixed-function oxygenase. Mass spectral analysis enabled the conversion of cyclohexane carboxylate to
p
-hydroxybenzoate by cell extracts to be established unequivocally, and all of our data were consistent with the pathway: cyclohexane carboxylate →
trans
-4-hydroxycyclohexane carboxylate → 4-ketocyclohexane carboxylate →
p
-hydroxybenzoate. The further metabolism of
p
-hydroxybenzoate proceeded by
meta
fission and by the oxidative branch of the 2-hydroxy-4-carboxymuconic semialde-hyde-cleaving pathway.
Outer membrane-dependent transport systems in Escherichia coli: turnover of TonB function
Authors: Kadner R J , McElhaney G
Published: January 2020

Recent reports demonstrated that the energy-dependent step of vitamin B12 uptake into cells of Escherichia coli rapidly declines after cessation either of the expression of the tonB gene or of general protein synthesis. It is shown here that inhibition of protein synthesis results in the decline, with similar kinetics, of all tonB-dependent processes, including sensitivity to colicins B and Ia, irreversible adsorption of phage phi80, and siderophore-mediated iron uptake. The role of ongoing TonB-dependent reactions on this lability of TonB function was investigated. Ferrichrome and the enterochelin precursor, 2,3-dihydroxybenzoate, caused both a moderate depression of B12 uptake activity in growing cells (reversed upon removal of the siderophore) and an acceleration of the loss of activity following inhibition of protein synthesis by addition of spectinomycin. Strains lacking the tonB-dependent siderophore uptake systems did not show these responses. The results suggest the consumption of tonB product during its action.
Freeze-fracture study of the filamentous, segmented microorganism attached to the murine small bowel
Authors: Snellen J E , Savage D C
Published: January 2020

A freeze-fracture study has provided new information about the filamentous, segmented microorganism known to live in the murine small bowel. The intracellular bodies produced by this microbe appear to arise by a modified sporogenesis so that they are enclosed in an envelopment membrane at least prior to release by the filament mother cell. At least some of the intracellular bodies divide while still within the mother cell, suggesting a reproductive role for these structures. The host epithelial membrane remains intact at the site of attachment, but does appear to have a reduced concentration of intramembrane particles. Changes in the host cytoplasm adjacent to the attachment site are documented and interpreted to be a sol-gel transformation which may stabilize the attachment socket.
Construction and characterization of amplifiable multicopy DNA cloning vehicles derived from the P15A cryptic miniplasmid
Authors: Chang A C , Cohen S N
Published: January 2020

Construction and characterization of a class of multicopy plasmid cloning vehicles containing the replication system of miniplasmid P15A are described. The constructed plasmids have cleavage sites within antibiotic resistance genes for a variety of commonly employed site-specific endonucleases, permitting convenient use of the insertional inactivation procedure for the selection of clones that contain hybrid DNA molecules. Although the constructed plasmids showed DNA sequence homology with the ColE1 plasmid within the replication region, were amplifiable by chloramphenicol or spectinomycin, required DNA polymerase I for replication, and shared other replication properties with ColE1, they were nevertheless compatible with ColE1. P15A-derived plasmids were not self-transmissible and were mobilized poorly by Hfr strains; however, mobilization was complemented by the presence of a ColE1 plasmid within the same cell.
Chromosome replication in an Escherichia coli dnaA mutant integratively suppressed by prophage P2
Authors: Kuempel P L , Duerr S A , Maglothin P D
Published: January 2020

Escherichia coli CRT4624-P2sig5 is a dnaA mutant in which integration of the prophage P2sig5 has occurred at the attP2II site (min 85). This strain was integratively suppressed, and when cells were shifted to 42 degrees C replication was initiated at a site in or near the P2 prophage. Initially, this replication occurred primarily in the direction that corresponds to the clockwise direction on the genetic map. Replication also occurred in the counterclockwise direction, but the initiation of replication in this direction occurred approximately 40 min later than the initiation of replication in the other direction. Because of this delay, the replication forks that traveled in the clockwise direction were the first to arrive in the region of the replication terminus. These replication forks ceased replication near the aroD locus (min 37), and it is proposed that the replication terminus is between the aroD and rac loci (min 31). A model is proposed for the cycle of chromosome replication in this strain at 42 degrees C.
Purification and properties of a second enzyme catalyzing the splitting of carbon-mercury linkages from mercury-resistant Pseudomonas K-62
Authors: Tezuka T , Tonomura K
Published: January 2020

An enzyme (splitting enzyme 2) which catalyzes the splitting of carbon-mercury linkage of arylmercury compounds was found in extracts of mercury-resistant Pseudomonas K-62. This enzyme was purified about 725-fold by treatment with streptomycin, precipitation with ammonium sulfate, and successive chromatography on Sephadex G-75 and diethylaminoethyl-cellulose. A purified preparation of the enzyme showed a single band in electrophoresis either on polyacrylamide or sodium dodecyl sulfate-containing polyacrylamide gels. The molecular weight of the enzyme was estimated to be 20,000 (determined by Sephadex G-75 gel filtration) 17,000 (determined by sodium dodecyl sulfate-polyacrylamide disc gel electrophoresis). The enzyme showed a Km of 180 micron and a Vmax of 3.1 mumol/min per mg for p-chloromercuribenzoic acid and a Km of 250 micron and a Vmax of 20 mumol/min per mg for phenylmercuric acetate. The optimum temperature and pH for the reaction were 40 degrees C and 5.0, respectively.
Biosynthesis of delta-aminolevulinic acid by blue-green algae (cyanobacteria)
Authors: Kipe-Nolt J A , Stevens S E , Stevens C L
Published: January 2020

When levulinic acid, a competitive inhibitor of delta-aminolevulinic acid dehydratase, was added to growing cultures of blue-green algae (cyanobacteria), delta-aminolevulinic acid was excreted into the medium and cell growth was inhibited.
Effect of near-UV light on Escherichia coli in the presence of 8-methoxypsoralen: wavelength dependency of killing, induction of prophage, and mutation
Authors: Fujita H , Suzuki K
Published: January 2020

Wavelength dependency of photo-inactivation and photoinduced reverse mutation of Escherichia coli sensitized with 8-methoxypsoralen, and wavelength dependency of photoinduction of lambda prophage from the sensitized lysogen were measured in a range of 298 to 400 nm. The most efficient sensitization for these biological effects was observed between 320 and 340 nm. In the presence of 8-methyoxypsoralen, the induced mutation frequency per lethal hit was highest of 298 nm in the range examined and was gradually decreased with increasing wavelength to a minimum frequency at 345 nm. This finding may be a reflection of the production of more than one type of lesions which have different efficiencies for mutation compared with the killing efficiency.
Pleiotropic effect of a rifampin-resistant mutation in Bacillus subtilis
Authors: Ryu J I
Published: January 2020

Rifampin-resistant (Rifr) mutants were isolated spontaneously from Bacillus subtilis strain 168. A fraction of the mutants did not grow on a minimal medium. A high concentration of one of the L-amino acids (glutamic acid, glutamine, arginine, proline, aspartic acid, or asparagine) was required to restore their growth on the medium. Further analysis of one of the mutants (strain RF 161) suggested that the mutant is unable to use ammonia as a nitrogen source and requires amino acids instead. Activity of glutamate synthase was not detected in the crude extract of the mutant. The Rifr mutation was closely located to cysA and the drug resistance was cotransformed with the property of amino acid requirement at 100% frequency. All revertants to prototrophy tested showed the rifampin-sensitive (Rifs) property. The activity of the DNA-dependent RNA polymerase of the mutant was resistant to rifampin. It is concluded that some alteration of RNA polymerase may cause absence of the activity of an enzyme involved in the nitrogen metabolism.
Induction and inhibition of the allantoin permease in Saccharomyces cerevisiae
Authors: Sumrada R , Zacharski C A , Turoscy V , Cooper T G
Published: January 2020

Allantoin uptake in Saccharomyces cerevisiae is mediated by an energy-dependent, low-Km, active transport system. However, there is at present little information concerning its regulation. In view of this, we investigated the control of alloantoin transport and found that it was regulated quite differently from the other pathway components. Preincubation of appropriate mutant cultures with purified allantoate (commercial preparations contain 17% allantoin), urea, or oxalurate did not significantly increase allantoin uptake. Preincubation with allantoin, however, resulted in a 10- to 15-fold increase in the rate of allantoin accumulation. Two allantoin analogs were also found to elicit dramatic increases in allantoin uptake. Hydantoin and hydantoin acetic acid were able to induce allantoin transport to 63 and 95% of the levels observed with allantoin. Neither of these compounds was able to serve as a sole nitrogen source for S. cerevisiae, and they may be non-metabolizable inducers of the allantoin permease. The rna1 gene product appeared to be required for allantoin permease induction, suggesting that control was exerted at the level of gene expression. In addition, we have shown that allantoin uptake is not unidirectional; efflux merely occurs at a very low rate. Allantoin uptake is also transinhibited by addition of certain amino acids to the culture medium, and several models concerning the operation of such inhibition were discussed.
Chromosome replication rate and cell shape in Escherichia coli: lack of coupling
Authors: Zaritsky A , Woldringh C L
Published: January 2020

The dimensions of Rep- cells of Escherichia coli K-12 were measured and compared with those of their Rep+ isogenic cells (both Thy-), Rep- cells cultivated identically were longer (but not wider), even though both strains were wider when the rate of chromosome replication was slowed down by lowering the thymine concentration supplied. This eliminates the possibility that cell shape is determined by this rate. Simulating Thy+ phenotype by adding deoxyguanosine resulted in shorter Rep- cells when growth was faster. This excludes a simple relationship between cell elongation and growth rate, but is consistent with a linear proportionality between the rate of surface synthesis and growth. Thymine limitation of fast-growing Thy- E. coli K-12 cells is shown to result in loss of their uniform shape and production of bizarre morphologies, apparently due to imbalanced synthesis of wall components.
Peptidase-deficient mutants of Escherichia coli
Authors: Miller C G , Schwartz G
Published: January 2020

Mutant derivatives of Escherichia coli K-12 deficient in several peptidases have been obtained. Mutants lacking a naphthylamidase, peptidase N, were isolated by screening for colonies unable to hydrolyze L-alanine beta-naphthylamide. Other mutants were isolated using positive selections for resistance to valine peptides. Mutants lacking peptidase A, a broad-specificity aminopeptidase, were obtained by selection for resistance to L-valyl-L-leucine amide. Mutants lacking a dipeptidase, peptidase D, were isolated from a pepN pepA strain by selection for resistance to L-valyl-glycine. Starting with a pepN pepA pepD strain, selection for resistance to L-valyl-glycyl-glycine or several other valine peptides produced mutants deficient in another aminopeptidase, peptidase B. Mutants resistant to L-valyl-L-proline lack peptidase Q, an activity capable of rapid hydrolysis of X-proline dipeptides. Using these selection procedures, a strain (CM89) lacking five different peptidases has been isolated. Although still sensitive to valine, this strain is resistant to a variety of valine di- and tripeptides. The ability of this strain to use peptides as sources of amino acids is much more restricted than that of wild-type E. coli strains. Strains containing only one of the five peptidases missing in CM89 have been constructed by transduction. The peptide utilization profiles of these strains show that each of the five peptidases can function during growth in the catabolism of peptides.
Copy numbers of coexisting plasmids in Escherichia coli K-12
Authors: Barth P T , Richards H , Datta N
Published: January 2020

A strain of Escherichia coli K-12 carrying eight compatible and distinguishable plasmids was constructed. The amounts of plasmid DNA (measured as supercoiled molecules) per chromosome in this strain was about equal to the sum of the plasmid DNAs, extracted under controlled conditions, from strains each carrying one of the eight plasmids. Analysis of these DNA preparations showed that each plasmid in the multiplasmid strain was present in the same proportion per chromosome as in the single-plasmid strains. Also the level of phenotypic expression of each plasmid in the multiplasmid strain was the same as in the single-plasmid strains. Each plasmid, therefore, appears to control its own copy number irrespective of the presence of other compatible plasmids.
Newly discovered polyamine, 2-hydroxyspermidine, in Pseudomonas acidovorans
Authors: Rosano C L , Hurwitz C , Bunce S C
Published: January 2020

A previously unknown hydroxylated polyamine has been recovered from Pseudomonas acidovorans 29. It has been identified as 2-hydroxyspermidine, N4-(3-aminopropyl)-1,4-diaminobutane-2-ol, by its chromatographic behavior, electrophoretic mobility, and reaction with metaperiodate. It can be synthesized enzymatically from 2-hydroxyputrescine by cell-free preparations from Escherichia coli or P. acidovorans 29 which contain propylamine transferase. It is interesting to note that the naturally occurring compound is the 2-hydroxyspermidine and not the 3-hydroxyspermidine, N1-(3-aminopropyl)-1,4-diaminobutane-2-ol, indicating that the propylamine transferase reacts preferentially with the amine distal to the hydroxyl group. A mixture of 2- and 3-hydroxyspermidines and hydroxyspermine was synthesized by reacting acrylonitrile with 2-hydroxyspermidine and catalytic reduction of the products with hydrogen. N-(gamma-aminopropyl)-beta-alanine, used to help identify the hydroxyspermidines, was synthesized from N-(3-aminopropyl)-3-aminopropanenitrile by hydrolysis with 10% NaOH.
Amine dehydrogenase of Pseudomonas putida: properties of the heme-prosthetic group
Authors: Durham D R , Perry J J
Published: January 2020

There was approximately five times more hemoprotein (amine dehydrogenase) in crude extracts obtained from Pseudomonas putida grown on benzylamine than present in extracts from succinate-grown cells. The difference (reduced minus oxidized) spectrum of the purified enzyme possessed alpha,beta, and gamma bands at 550, 523, and 416 nm, respectively. The difference spectrum of the pyridine hemochrome derivative had absorption maxima at 416, 520, and 550 nm. These results, together with the fact that the heme group was covalently bound to the enzyme, indicated that the amine dehydrogenase from P. putida was a hemoprotein which contained heme c. The heme content was calculated at 2.01 mol/mol of enzyme. The enzyme was composed of two nonidentical subunits, but heme was present solely in the heavier unit. Carbon monoxide did not inhibit enzymatic activity, nor would it combine with the reduced or oxidized form of the enzyme. Amine dehydrogenase activity was inhibited by carbonyl agents with semicarbazide and cuprizone acting noncompetitively, whereas KCN and isoniazid inhibited by competitive and uncompetitive mechanisms, respectively. Spectral observations suggested that inhibition by these reagents was not due to an interaction with the heme moiety.
Intraperiplasmic growth of Bdellovibrio bacteriovorus 109J: solubilization of Escherichia coli peptidoglycan
Authors: Thomashow M F , Rittenberg S C
Published: January 2020

During penetration of Bdellovibrio bacteriovorus into Escherchia coli, two enzymatic activities, a glycanase and a peptidase, rapidly solubilized some 10 to 15% of the E. coli peptidoglycan. The glycanase activity, which solubilizes peptidoglycan amino sugars, came to a sharp halt with completion of the penetration process. Peptidase activity, which cleaves diaminopimelic acid residues from the peptidoglycan, continued, but at a decreasing rate. By 90 min after bdellovibrio attack, some 30% of the initial E. coli diaminopimelic acid residues were solubilized and present in the culture fluid as free diaminopimelic acid. During bdellovibrio penetration some 25% of the lipopolysaccharide glucosamine was also solubilized by an as yet undefined enzymatic activity that yielded products having molecular weights below 2,000. The solubilization of E. coli lipopolysaccharide glucosamine also terminated at completion of bdellovibrio penetration. At the end of bdellovibrio growth, a second period of rapid solubilization of bdelloplast peptidoglycan began which resulted in lysis of the bdelloplast and complete solubilization of the peptidoglycan amino sugars and diaminopimelic acid. The final lytic enzyme(s) was synthesized just before the time of lysis.
Modulation of an apparent mRNA pool for extracellular protease in Bacillus amyloliquefaciens
Authors: O'Connor R , Elliott W H , May B K
Published: January 2020

Late-log-phase cells of Bacillus amyloliquefaciens have the unusual capacity to produce extracellular protease for over 60 min in the presence of rifampin or actinomycin D at levels which strongly inhibit incorporation of amino acids into cellular protein. If cells are incubated in the presence of high levels of amino acids for 75 min this capacity is exhausted, but it is retained if the incubation is carried out in low levels of amino acids. Transfer of exhausted cells from high to low concentrations of amino acids results in a progressive recovery of the capacity for rifampin-actinomycin-insensitive protease production. The results seem best explained on the basis of the accumulation of a reserve pool of mRNA for extracellular protease. Measurement of the apparent mRNA pool size over 12 h shows a cyclical rise and fall, and these changes correlate with a periodic variation of the rate of protease production. A working hypothesis is presented to account for these observations in terms of a novel control situation over protease mRNA transcription.
Altered nuclear pore diameters in G1-arrested cells of the yeast Saccharomyces cerevisiae
Authors: Willison J H , Johnston G C
Published: January 2020

Nuclear pores in cells of the yeast Saccharomyces cerevisiae were examined by using the freeze-fracture technique. Nuclear pore diameters in actively growing cells appear to be exclusively of the normal diameter (75 to 115 nm), whereas some pore diameters in abnormally small G1-arrested cells produced by nitrogen starvation are unusually wide (120 to 160 nm). There may be a correlation between nuclear pore size and nuclear envelope size, the larger pores tending to occur in the smaller envelopes. The finding suggests that nuclear pore diameter may not function in regulating the flow of informational molecules from nucleus to cytoplasm, but may be implicated in regulating the flow of substrates into the nucleus.
Cell envelope alterations in antibiotic-sensitive and-resistant strains of Neisseria gonorrhoeae
Authors: Guymon L F , Walstad D L , Sparling P F
Published: January 2020

The cell envelopes of antibiotic-resistant and -sensitive isogenic strains of Neisseria gonorrhoeae were analyzed to determine whether acquisition of genetic loci for altered antibiotic sensitivity was accompanied by alterations in cell envelope composition. No differences in the composition of phospholipids and lipopolysaccharides were noted. Acquisition of mtr-2, which results in low-level, nonspecific increased resistance to multiple antibiotics, dyes, and detergents, was accompanied by a sevenfold increase in the amount of a minor, 52,000-molecular-weight outer membrane protein and a 32% increase in the extent of peptidoglycan cross-linking. Subsequent addition of the nonspecific hypersensitivity loci env-1 or env-2 to a strain carrying mtr-2 resulted in reversal of the phenotypic resistance determined by mtr-2 and marked reduction in both the amount of the 52,000-molecular-weight outer membrane protein and the extent of peptidoglycan cross-linking. Introduction of penB2, which results in a fourfold increase in resistance to penicillin and tetracycline, was accompanied by the disappearance of the principal outer membrane protein of the wild-type strain (molecular weight, 36,900) and the appearance of a new species of the principal outer membrane protein (molecular weight, 39,400) in the transformant.
Evolution of propanediol utilization in Escherichia coli: mutant with improved substrate-scavenging power
Authors: Hacking A J , Aguilar J , Lin E C
Published: January 2020

Wild-type strains of Escherichia coli are unable to use L-1,2-propanediol as a carbon and energy source. A series of mutants, able to grow on this compound at progressively faster rates, had been isolated by repeated transfers to a medium containing 20 mM L-1,2-propanediol. These strains synthesize at high constitutive levels a propanediolmicotinamide adenine dinucleotide oxidoreductase, an enzyme serving as a lactaldehyde during L-fucose fermentation by wild type cells. In this study, a mutant that can grow rapidly on the novel carbon source was subjected to further selection in a medium containing L-1,2-propanediol never exceeding 0.5 mM to obtain a derivative that has an increased power to extract the substrate from the medium. The emerging mutant exhibited four changes at the enzymatic level: (i) fuculose 1-phosphate aldolase activity is lost; (ii) the constitutive propanediol oxidoreductase activity is increased in its level; (iii) lactaldehyde dehydrogenase becomes constitutive and shows an elevated specific activity in crude extracts; and (iv) at low concentrations of propanediol, the facilitated diffusion across the cell membrane is enhanced. Changes two to four seem to act in concert in the trapping of propanediol by hastening its rate of entry and conversion to an ionized metabolite, lactate.
Relationship between extracellular enzymes and cell growth during the cell cycle of the fission yeast Schizosaccharomyces pombe: acid phosphatase
Authors: Miyata M , Miyata H
Published: January 2020

By using the intact cells of the fission yeast Schizosaccharomyces pombe, the activity of acid phosphatase (EC 3.1.3.2) was compared through the cell cycle with the growth in cell length as a measure of cell growth. The cells of a growing asynchronous culture increased exponentially in number and in total enzyme activity, but remained constant in average length and in specific activity, In a synchronous culture prepared by selection or by induction, the specific activity was periodic in parallel with the increase in average cell length. When hydroxyurea was added to an asynchronous or a synchronous culture by selection, both specific and total activity followed the same continuous pattern as the growth in cell length after the stoppage of cell division. When oversized cells produced by a hydroxyurea pulse treatment to the culture previously syndronized by selection were transferred to a poor medium, they divided synchronously but could hardly grow in the total cell length. In this experimental situation, the total enzyme activity also scarcely increased through three division cycles. These results suggested that the increase in acid phosphatase in dependent on cell elongation.
Relationship between catabolism of glycerol and metabolism of hexosephosphate derivatives by Pseudomonas aeruginosa
Authors: Heath H E , Gaudy E T
Published: January 2020

The relationship between catabolism of glycerol and metabolism of hexosephosphate derivatives in Pseudomonas aeruginosa was studied by comparing the growth on glycerol and enzymatic constitution of strain PAO with these characteristics of glucose-catabolic mutants and revertants. Growth of strain PAO on glycerol induced a catabolic oxidized nicotinamide adenine dinucleotide-linked glyceraldehyde-phosphate dehydrogenase and seven glucose-catabolic enzymes. The results indicated that these enzymes were induced by a six-carbon metabolite of glucose. All strains possessed a constitutive anabolic Embden-Meyerhof-Parnas pathway allowing limited conversion of glycerol-derived triosephosphate to hexosephosphate derivatives, which was consistent with induction of these enzymes by glycerol. Phosphogluconate dehydratase-deficient mutants grew on glycerol. However, mutants lacking both phosphogluconate dehydrogenase and phosphogluconate dehydratase were unable to grow on glycerol, although these strains possessed all of the enzymes needed for degradation of glycerol. These mutants apparently were inhibited by hexosephosphate derivatives, which originated from glycerol-derived triosephosphate and could not be dissimilated. This conclusion was supported by the fact that revertants regaining only a limited capacity to degrade 6-phosphogluconate were glycerol positive but remained glucose negative.
Classes of Anabaena variabilis mutants with oxygen-sensitive nitrogenase activity
Authors: Haury J F , Wolk C P
Published: January 2020

Mutants of Anabaena variabilis deficient in the envelope glycolipids of heterocysts have no or very low nitrogenase activity when assayed aerobically. Revertants capable of aerobic growth on N2 have increased quantities of these glycolipids. Among mutants which require fixed nitrogen for growth in air and which have a normal complement of glycolipids, one expresses high nitrogenase activity at low oxygen tension. Three others show high nitrogenase activity only in the presence of dithionite and are therefore impaired in electron transfer.
Thermal adaptation in yeast: obligate psychrophiles are obligate aerobes, and obligate thermophiles are facultative anaerobes
Authors: Watson K , Arthur H , Morton H
Published: January 2020

The obligate psychrophilic yeasts Torulopsis psychrophila, T. austromarina, Leucosporidium frigidum, L. gelidum, and L. nivalis were obligate aerobes and were unable to grow anaerobically. In contrast, the obligate thermophilic yeasts T. bovina, T. pintolopesii, Candida slooffii, and Saccharomyces telluris were facultative anaerobes.
Ureotelism and ammonotelism in trypanosomatids
Authors: Yoshida N , Camargo E P
Published: January 2020

According to their genera, trypanosomatids excrete urea, ammonia, or both. Species of Herpetomonas and Trypanosoma are ammonotelic. Species of Leishmania, Leptomonas, Crithidia, and Blastocrithidia can be ureotelic, ammonotelic, or both, depending on growth media composition.
Metabolism of RNA-ribose by Bdellovibrio bacteriovorus during intraperiplasmic growth on Escherichia coli
Authors: Hespell R B , Odelson D A
Published: January 2020

During intraperiplasmic growth of Bdellovibrio bacteriovorus 109J on Escherichia coli some 30 to 60% of the initial E. coli RNA-ribose disappeared as cell-associated orcinol-positive material. The levels of RNA-ribose in the suspending buffer after growth together with the RNA-ribose used for bdellovibrio DNA synthesis accounted for 50% or less of the missing RNA-ribose. With intraperiplasmic growth in the presence of added U-14C-labeled CMP, GMP, or UMP, radioactivity was found both in the respired CO2 and incorporated into the bdellovibrio cell components. The addition of exogenous unlabeled ribonucleotides markedly reduced the amounts of both the 14CO2 and 14C incorporated into the progeny bdellovibrios. During intraperiplasmic growth of B. bacteriovorus on [U-14C]ribose-labeled E. coli BJ565, ca. 74% and ca. 19% of the initial 14C was incorporated into the progeny bdellovibrios and respired CO2, respectively. Under similar growth conditions, the addition of glutamate substantially reduced only the 14CO2; however, added ribonucleotides reduced both the 14CO2 and the 14C incorporated into the progeny bdellovibrios. No similar effects were found with added ribose-5-phosphate. The distribution of 14C in the major cell components was similar in progeny bdellovibrios whether obtained from growth on [U-14C]ribose-labeled E. coli BJ565 or from E. coli plus added U-14C-labeled ribonucleotides. After intraperiplasmic growth of B. bacteriovorus on [5,6-3H-]uracil-[U-14C]ribose-labeled E. coli BJ565 (normal or heat treated), the whole-cell 14C/3H ratio of the progeny bdellovibrios was some 50% greater and reflected the higher 14C/3H ratios found in the cell fractions. B. bacteriovorus and E. coli cell extracts both contained 5'-nucleotidase, uridine phosphorylase, purine phosphorylase, deoxyribose-5-phosphate aldolase, transketolase, thymidine phosphorylase, phosphodeoxyribomutase, and transaldolase enzyme activities. The latter three enzyme activities were either absent or very low in cell extracts prepared from heat-treated E. coli cells. It is concluded that during intraperiplasmic growth B. bacteriovorus degrades some 20 to 40% of the ribonucleotides derived from the initial E. coli RNA into the base and ribose-1-phosphate moieties. The ribose-1-phosphate is further metabolized by B. bacteriovorus both for energy production and for biosynthesis, of non-nucleic acid cell material. In addition, the data indicate that during intraperiplasmic growth B. bacteriovorus can metabolize ribose only if this compound is available to it as the ribonucleoside monophosphate.
Constancy of growth on simple and complex media
Authors: Wang C H , Koch A L
Published: January 2020

An apparatus has been developed in which bacterial growth can be measured very precisely over short intervals of time. Its precision is presented and used to assess the constancy of growth in batch culture. Under certain conditions, i.e., Luria broth or 0.2% glucose-M9 medium at very low cell densities, the specific growth rate of Escherichia coli appeared to be constant within the measurement limits of the method. In succinate minimal medium, the growth rate increased gradually over several days and never became constant. With nutrient broth and with Luria broth, growth slowed progressively at moderate cell densities within the range considered to be in the logarithmic phase of growth. In addition, temporary slowdown in growth rate occurred in these two complex media at characteristic cell densities. These gradual increases in succinate minimal medium and temporary slowdowns in the complex media would be undetectable without precise measurements and may have been a source of variability in many bacteriological studies.
Tight-binding repressors of the lac operon: selection system and in vitro analysis
Authors: Pfahl M
Published: January 2020

The isolation and characterization of altered repressors of the lac operon which have an increased affinity for an operator should give useful clues about the molecular basis for the very tight and specific interaction between repressor and operator. A selection system has been devised which allows the isolation of such repressor mutants. This system selects for mutant repressors which can overcome lac operator-constitutive (Oc) mutations. By using in vivo assays, 24 candidates were obtained which, compared with wild type, have an increased trans effect of their repressor on one or several Oc operators. Three of these candidates have been investigated in vitro; the affinity of their repressor for inducer was unchanged, whereas the affinity for wild-type operator was increased 15-, 86-, and 262-fold, respectively.
Effect of levulinic acid on pigment biosynthesis in Agmenellum quadruplicatum
Authors: Kipe-Nolt J A , Stevens S E
Published: January 2020

When levulinic acid was added to a growing culture of the cyanobacterium (blue-green alga) Agmenellum quadruplicatum PR-6, delta-aminoelevulinic acid accumulated in the medium and chlorophyll a synthesis and cell growth were inhibited, but there was a small amount of c-phycocyanin synthesis. The amount of delta-aminolevulinic acid produced in the treated culture did not fully account for the amount of pigment synthesized in the untreated control. Levulinic acid and either sodium nitrate or ammonium chloride were added to nitrogen-starved cultures of PR-6, and delta-aminolevulinic acid production and chlorophyll a and c-phycocyanin content were monitored. When ammonium chloride was added as a nitrogen source after nitrogen starvation, the cells recovered more rapidly than when sodium nitrate was added as a nitrogen source. In cultures recovering from nitrogen starvation, synthesis of c-phycocyanin occurred before synthesis of chlorophyll a.
ColE1 hybrid plasmids for Escherichia coli genes of glycolysis and the hexose monophosphate shunt
Authors: Thomson J , Gerstenberger P D , Goldberg D E , Gociar E , Orozco de Silva A , Fraenkel D G
Published: January 2020

The Clarke-Carbon clone bank carrying ColE1-Escherichia coli DNA has been screened by conjugation for complementation of glycolysis and hexose monophosphate shunt mutations. Plasmids were identified for phosphofructokinase (pfkA), triose phosphate isomerase (tpi), phosphoglucose isomerase (pgi), glucose-6-phosphate dehydrogenase (zwf), gluconate-6-phosphate dehydrogenase (gnd), enolase (eno), phosphoglycerate kinase (pgk), and fructose-1,6-P2 aldolase (fda). Enzyme levels for the plasmid-carried gene ranged, for the various plasmids, from 4- to 25-fold the normal level.
Purification and properties of an inducible beta-galactosidase isolated from the yeast Kluyveromyces lactis
Authors: Dickson R C , Dickson L R , Markin J S
Published: January 2020

beta-Galactosidase (EC 3.2.1.32) was purified 80-fold from the yeast Kluyveromyces lactis induced for this enzyme by growth on lactose. When the purified enzyme was subjected to electrophoresis on an acrylamide gel in the presence of sodium dodecyl sulfate, one protein with an apparent molecular weight of 135,000 was observed. The enzyme has a sedimentation coefficient of 9.6S. This beta-galactosidase and the one from Escherichia coli are not antigenically related. Maximal enzyme activity requires Na+ and Mn2+ and a reducing agent. beta-Galactosidase has Km values of 12 to 17 and 1.6 mM for lactose and o-nitrophenyl-beta-D-galactoside, respectively. The hydrolase and transgalactosylase activities of the enzyme are similar to those of E. coli beta-galactosidase.
Regulation of polyamine and streptomycin transport during stringent and relaxed control in Escherichia coli
Authors: Höltje J V
Published: January 2020

Inhibition of polyamine uptake was observed during amino acid depletion in a stringent strain of Escherichia coli CP78 but not in a relaxed strain (CP79). Chloramphenicol was shown partially to relieve the inhibition of uptake. Stringent cells which were induced for a transport system common to both polyamines and streptomycin were found to restrict the uptake of spermidine as well as streptomycin.
Simple method for identification of plasmid-coded proteins
Authors: Sancar A , Hack A M , Rupp W D
Published: January 2020

Proteins encoded by plasmid DNA are specifically labeled in UV-irradiated cells of Escherichia coli carrying recA and uvrA mutations because extensive degradation of the chromosome DNA occurs concurrently with amplification of plasmid DNA.
Dissociation of the NIC plasmid aggregate in Pseudomonas putida
Authors: Thacker R , Gunsalus I C
Published: January 2020

The NIC plasmid on conjugal transfer from Pseudomonas convexa Pc 1 to Pseudomonas putida PpG 1 dissociates into an independent fertility factor T and a nontransmissible NIC structural gene plasmid.
Chromosomal regulation of sexual expression in Escherichia coli
Authors: Lerner T J , Zinder N D
Published: January 2020

We report a genetic analysis of a recessive chromosomal mutation of Escherichia coli K-12 that is responsibel for masking the sexual expression of an F factor that it carries. We call this new bacterial gene, which is closely linked to thr, fex, for F expression.
Variation in the structure and bacteriophage-inactivating capacity of Salmonella anatum lipopolysaccharide as a function of growth temperature
Authors: McConnell M , Wright A
Published: January 2020

Growth temperature affects both the structure and the phage-inactivating capacity of Salmonella anatum A1 lipopolysaccharide. Whereas S. anatum cells normally synthesize smooth lipopolysaccharide when grown at physiological temperature (37 degrees C), a partial smooth-rough transition occurs when cells are grown at low temperature (20 to 25 degrees C). The synthesis at low growth temperature of lipopolysaccharide molecules lacking O-antigen was detected both by increased sensitivity of cells to the rough-specific bacteriophage Felix O-1 and by fractionation of oligosaccharides derived from lipopolysaccharide by mild acid hydrolysis. Growth temperature-induced changes in the structure of S. anatum A1 lipopolysaccharide also affected its ability to inactivate epsilon15, a bacteriophage that binds initially to the O-antigen portion of the molecule. Purified lipopolysaccharide prepared from cells grown at low growth temperature exhibited a higher in vitro phage-inactivating capacity than did lipopolysaccharide prepared from cells grown at physiological temperature (37 degrees C).
Circadian rhythms in Neurospora crassa: effects of unsaturated fatty acids
Authors: Brody S , Martins S A
Published: January 2020

Employing a fatty acid-requiring strain (bd csp cel) of Neurospora crassa, the 21.5-h period of the circadian spore-forming rhythm was manipulated by fatty acid supplementation. The addition to the medium of an unsaturated fatty acid (oleic, linoleic, or linolenic acid) lengthened the period to 26, 40, or 33 h, respectively. Ther period-lengthening effect of linoleic acid was proportional to its concentration up to 1.3 X 10(-4) M, and also was reversed by the addition to the medium of a saturated fatty acid, palmitic acid. None of these period-lengthening effects was observed in the prototrophic strain (bd csp cel+).
Chromosome replication and cell division in plasmid-containing Escherichia coli B/r
Authors: Weinberger M , Helmstetter C E
Published: January 2020

The kinetics of chromosome replication and cell division have been examined in recA mutants of Escherichia coli B/r containing F' plasmids of various sizes. Plasmid-mediated alterations in growth properties were detected only with the presence of the larger F' plasmids, and were reflected in decreased mean cell sizes and growth rates. The lengths of C and D in all plasmid-containing strains were in accord with the values for plasmid-free parental strains growing with similar generations times. The findings were consistent with an absence of competition between the chromosomal and extrachromosomal replicons for rate-limiting components involved in the initiation of deoxyribonucleic acid synthesis or in the elongation of deoxyribonucleic acid chains.
Gene dosage effects on the synthesis of maltase in yeast
Authors: Mowshowitz D B
Published: January 2020

Inbred strains of Saccharomyces cerevisiae carrying MAL1, MAL2, or MAL6 in a common background were used to construct (i) homo- or heterozygous diploids carrying one or two active alleles of a single MAL locus (MAL1, MAL2, or MAL6) and (ii) triploids carrying one, two, or three active alleles of MAL2. The diploid and triploid strains were used to investigate gene dosage effects of the differential rate of maltase synthesis (delta enzyme activity/delta growth) and the kinetics of induction (for MAL2). All three MAL loci exhibited a gene dosage effect on the differential rate of maltase synthesis; MAL2 also exhibited a gene dosage effect on the kinetics of induction. The dosage effects of the MAL1 and MAL6 loci were additive, but the effects of the MAL2 locus were not; the magnitude of the MAL2 gene dosage effect decreased with increasing dosage. These results are compatible with the current genetic evidence that the MAL genes are regulatory loci if the product(s) of the MAL1 and MAL6 locus is produced in limiting amounts but the product(s) of the MAL2 locus is produced in excess, except at very low genes dosages.
Transmission of mitochondrial deoxyribonucleic acid in Neurospora crassa sexual crosses
Authors: Mannella C A , Pittenger T H , Lambowitz A M
Published: January 2020

Neurospora crassa mitochondrial deoxyribonucleic acid shows strict uniparental inheritance in sexual crosses, with a notable absence of mixtures and recombinant types that appear frequently in heteroplasmons.
Derepression of nitrogenase activity in glutamine auxotrophs of Rhodopseudomonas capsulata
Authors: Wall J D , Gest H
Published: January 2020

In contrast to wild-type cells, glutamine auxotrophs of the photosynthetic bacterium Rhodopseudomonas capsulata synthesize nitrogenase, produce H2 (catalyzed by nitrogenase), and continue to reduce dinitrogen to ammonia in the presence of exogenous NH4+. The glutamine synthetase activity of such mutants is less than 2% of that observed in the wild type. It appears that glutamine synthetase plays a significant role in regulation of nitrogenase synthesis in R. capsulata.
Inactivation of Neurospora crassa conidia by singlet molecular oxygen generated by a photosensitized reaction
Authors: Shimizu M , Egashira T , Takahama U
Published: January 2020

Photodynamic damage of Neurospora crassa conidia was studied in the presence of the photosensitizing dye, toluidine blue O. Conidia which germinated to form colonies decreased in number as irradiation time became longer. The photoinactivation of conidia was suppressed by azide, bovine serum albumin, and histidine, and was stimulated in deuterium oxide. Wild-type conidia were less sensitive to the irradiation than albino conidia. In the wild-type, carotenoid-enriched conidia were more resistant against the lethal damage than the conidia which contained small amounts of carotenoids. These results suggest that singlet molecular oxygen causes photodynamic lethal damage to N. crassa conidia and that singlet molecular oxygen is quenched by endogenous carotenoids.
Role of Pipecolic Acid in the Biosynthesis of Lysine in
Rhodotorula glutinis
Authors: Kinzel Jerome J. , Bhattacharjee J. K.
Published: January 2020

The role of pipecolic acid in the biosynthesis of lysine was investigated in
Rhodotorula glutinis
, an aerobic red yeast. Supplementation of pipecolic acid in the minimal medium supported the growth of mutants
lys2, lys3
, and
lys5
; α-aminoadipic acid supported the growth of
lys5
; but neither α-aminoadipic acid nor pipecolic acid supported the growth of mutants MNNG42 and MNNG37. During the growth of the appropriate mutants, pipecolic acid was removed from the growth medium and the intracellular pool. In tracer experiments, radioactivity from [
14
C]pipecolic acid was selectively incorporated into the cellular lysine of
lys5
and the wild-type strain.
l
-Pipecolic acid-dependent enzyme activity did not require any cofactor and was inhibited by mercuric chloride and potassium cyanide. This activity was present in the wild-type strain and all of the mutants tested and was repressed in mutant
lys5
when grown in the presence of higher concentration of lysine. The reaction product of pipecolic acid was converted to saccharopine by
lys5
enzyme in the presence of glutamate and reduced nicotin-amide adenine dinucleotide phosphate. Mutant MNNG37 lacked the saccharopine dehydrogenase activity, indicating that this step is involved in the conversion of α-aminoadipic acid and pipecolic acid to lysine. Mutants MNNG37 and MNNG42 accumulated a
p
-dimethylaminobenzaldehyde-reacting product in the culture supernatant and in the intracellular pool. Chromatographic properties of the
p
-dimethylaminobenzaldehyde adduct and that of the pipecolic acid-dependent reaction product were similar. The reaction product and the accumulation product were characterized on the basis of mass and absorption spectra as α-aminoadipic-semialdehyde, which in solution remains in equilibrium with Δ
1
-piperideine-6-carboxylic acid. Since α-aminoadipic-semialdehyde is a known intermediate of the α-aminoadipic acid pathway for the biosynthesis of lysine, it is concluded that pipecolic acid is converted to lysine in
R. glutinis
via α-aminoadipic-semialdehyde and saccharopine.