bluuebunny/crossref_metadata_2025 huggingface dataset:
Mating Pheromones of
Saccharomyces kluyveri
: Pheromone Interactions Between
Saccharomyces kluyveri
and
Saccharomyces cerevisiae
Authors: McCullough John , Herskowitz Ira
Published: January 2020

Saccharomyces kluyveri
is a heterothallic yeast with two allelic mating types denoted as
a-k
and α-
k
by analogy with
Saccharomyces cerevisiae
and from the work described here.
S. kluyveri
produces mating pheromones analogous to those of
S. cerevisiae
, but which appear to have different specificity.
S. kluyveri
thus differs from
S. cerevisiae, Hansenula wingei
, and
Schizosaccharomyces pombe
in that it exhibits both strong constitutive agglutination and mating pheromones. α-
k
cells produce a pheromone (“α-
k
-factor”) which causes
a-k
cells to arrest in the G1 phase of the cell cycle and to undergo a morphological change. After a period of time dependent on the concentration of α-
k
-factor, cells exposed to the factor resume cell division. α-
k
-factor has no effect on
a-k
/α-
k
diploids or on α-
k
cells, but at high concentration does induce G1 arrest of
S. cerevisiae
a
cells (
a
-c).
a-k
cells produce a pheromone (“
a-k
-factor”) which causes α-
k
cells to exhibit a morphological change. In addition,
a-k
cells exhibit the Bar phenotype with respect to α-
k
-factor. Partially purified preparations of
S. cerevisiae
α-factor are more active in inducing G1 arrest of
a-k
cells than of
a
-c cells. A more purified preparation of α-c-factor is less active against
a-k
cells than
a
-c cells, suggesting that an additional factor (KRE,
kluyveri
response enhancer) may be lost during purification. Attempts to mate
S. kluyveri
and
S. cerevisiae
cells by prototroph selection and by cell-to-cell mating have been unsuccessful with all combinations of mating types. Thus,
S. cerevisiae
and
S. kluyveri
are incompatible for mating even though their pheromones exhibit some physiological cross-reaction.
Isolation and characterization of bacterial flagellar hook proteins from salmonellae and Escherichia coli
Authors: Kagawa H , Aizawa S I , Yamaguchi S , Ishizu J I
Published: January 2020

Flagellar hook proteins from Salmonella and Escherichia coli were dissociated in acid and purified by diethylamino-ethyl-cellulose column chromatography. These two proteins had the same electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels. However, analytical electrofocusing patterns showed that these proteins had different isoelectric points (4.7 for Salmonella typhimurium and 4.4 for E. coli). Immunodiffusion and immuno-electron microscopy carried out with antisera prepared against purified hook proteins from S. typhimurium and E. coli showed that these antisera reacted with both hooks. Affinity chromatography allowed separation of antibodies specific for hook proteins from each bacterial species. These results indicate that the hook proteins share common antigenic determinants as well as specific antigens, although the specificity is not quantitatively resolved. From comparisons of the amino acid composition of the hook proteins and flagellins, it was concluded that the differences between flagellins from S. typhimurium and E. coli were larger than those between hook proteins from these species.
Mapping hisS, the structural gene for histidyl-transfer ribonucleic acid synthetase, in Escherichia coli
Authors: Parker J , Fishman S E
Published: January 2020

The structural gene for histidyl-tRNA synthetase was localized to 53.8 min on the Escherichia coli genome. The gene order in this region was determined to be dapE-purC-upp-purG-(guaA, guaB)-hisS-glyA.
Metabolism of pyrimidine bases and nucleosides in Neisseria meningitidis
Authors: Jyssum S , Jyssum K
Published: January 2020

In Neisseria meningitidis, uridine, deoxyuridine, cytosine, cytidine, or deoxycytidine could not be used by uracil-requiring mutants as pyrimidine sources. Consistent with these findings, only 5-fluorouracil of the different fluoropyrimidine bases and nucleosides showed any inhibitory effect on the growth of four prototrophic strains of N. meningitidis. Likewise, only radioactive uracil was readily incorporated into nucleic acids, whereas uptake of radioactive uridine, cytosine, or cytidine could not be demonstrated. Uracil was converted to uridine 5'-monophosphate by uracil phosphoribosyltransferase, whereas enzyme activities for conversion of cytosine or any of the nucleosides were not detectable in meningococcal extracts.
Amino Acid Catabolism and Malic Enzyme in Differentiating
Dictyostelium discoideum
Authors: Kelleher Joanne K. , Kelly Patrick J. , Wright Barbara E.
Published: January 2020

Amino acids produced from protein degradation are the major energy source for differentiation and aging in
Dictyostelium discoideum
. Considering the reactions involved in the conversion of amino acids from an average protein into tricarboxylic acid cycle intermediates, a route from a cycle intermediate (probably malate) to acetyl coenzyme A is required for the complete utilization of amino acids. Citrate was isolated from cells pulse-labeled with
14
C-labeled amino acids and was cleaved with citrate lyase. When cells were pulse-labeled with [
U
-
14
C]-glutamate the specific radioactivity of the acetate and oxaloacetate portions of citrate were consistent with the conclusion that one-third of the carbon flowing through the tricarboxylic acid cycle is removed for the synthesis of acetyl coenzyme A. The data were also consistent with the patterns of carbon flux required to maintain steady-state levels of cycle intermediates in cells catabolizing amino acids. It is suggested that the malic enzyme (EC 1.1.1.40) catalyzes the synthesis of acetyl coenzyme A from malate and is responsible for the observed citrate labeling pattern. In cell extracts the activity of this enzyme increased markedly with the onset of differentiation. The properties of partially purified (40-fold) malic enzyme isolated at culmination indicated that the enzyme was allosteric and was positively affected by aspartate and glutamate. Thus, amino acid production from protein degradation would stimulate a reaction essential for the efficient utilization of these amino acids for energy.
Protein and ribonucleic acid syntheses in heat-damaged and heat-killed Escherichia coli
Authors: Dean R G , McGroarty E J
Published: January 2020

Protein and ribonucleic acid (RNA) syntheses were measured in both lethally injured and thermally damaged viable cells after heating at lethal temperatures. Immediately after heating, cells were incubated in growth media containing either [14C]leucine or [3H]uracil. The labeled cells were subsequently treated with penicillin. Viable cells were shown to lyse, and the intact nonviable cells were collected by centrifugation. The results showed that after heating, protein and RNA synthesis were reinitiated in the penicillin-sensitive cell population, but there was no detectable protein or RNA synthesis in the heat-killed cells which were resistant to penicillin. The lack of protein or RNA synthesis in lethally damaged cells during the entire recovery period may be interpreted to reflect the lethal thermal damage.
Biochemical and topographical studies on Escherichia coli cell surface. IV. Giant spheroplast formation from a filamentous cell
Authors: Onitsuka M O , Rikihisa Y , Maruyama H B
Published: January 2020

Long, nonseptate filamentous cells consisting of 5 to 40 single-cell unit lengths were formed from Escherichia coli surface mutant ONT-3 by treatment with a sublethal concentration of sodium dodecyl sylfate. As distinct from several other elongated cells (e.g., thymine-starved filaments), it was found here that stable giant spheroplasts, 5 to 10 micrometers in diameter, were produced by the action of lysozyme in the presence of bovine serum albumin via the gradual fusion of distinct spheroplasting bulbs.
Membranes of Rhodopseudomonas sphaeroides: effect of cerulenin on assembly of chromatophore membrane
Authors: Broglie R M , Niederman R A
Published: January 2020

The effects of cerulenin were investigated in Rhodopseudomonas sphaeroides to elucidate further the mechanisms controlling the assembly of the chromatophore membrane. When this potent inhibitor of fatty acid biosynthesis was added to photosynthetically grown cultures, there was an immediate cessation of phospholipid, bacteriochlorophyll a, carotenoid, and ubiquinone formation. Concurrently, there was also a marked decrease in the rate of incorporation of protein into the chromatophore membrane. In contrast, only a small decrease in the rate of soluble and cell envelope protein synthesis was observed and, in chemotrophically grown cells, protein continued to be incorporated into both the cytoplasmic and outer membranes. The removal of delta-aminolaevulinate from mutant H-5 of R. sphaeroides, which requires this porphyrin precursor, was reexamined to determine whether cerulenin-induced cessation of chromatophore protein incorporation was due solely to blocked bacteriochlorophyll a synthesis. In the deprived H-5 cells, inhibition of [35S]methionine incorporation into chromatophores was confined mainly to apoproteins of bacteriochlorophyll a complexes. Other minor chromatophore proteins continued to be inserted to a greater extent than in cerulenin-treated wild type where phospholipid synthesis has also ceased. These results indicated that the assembly of the chromatophore membrane is under strict regulatory control involving concomitant phospholipid, pigment, and protein syntheses.
Isolation and preliminary characterization of Saccharomyces cerevisiae proline auxotrophs
Authors: Brandriss M C
Published: January 2020

Proline-requiring mutants of Saccharomyces cerevisiae were isolated. Each mutation is recessive and is inherited as expected for a single nuclear gene. Three complementation groups cold be defined which are believed to correspond to mutations in the three genes (pro1, pro2, and pro3) coding for the three enzymes of the pathway. Mutants defective in the pro1 and pro2 genes can be satisfied by arginine or ornithine as well as proline. This suggests that the blocks are in steps leading to glutamate semialdehyde, either in glutamyl kinase or glutamyl phosphate reductase. A pro3 mutant has been shown by enzyme assay to be deficient in delta 1-pyrroline-5-carboxylate reductase which converts pyrroline-5-carboxylate to proline. A unique feature of yeast proline auxotrophs is their failure to grown on the rich medium, yeast extract-peptone-glucose. This failure is not understood at present, although it accounts for the absence of proline auxotrophs in previous screening for amino acid auxotrophy.
Yeast cytochrome c-specific protein-lysine methyltransferase: coordinate regulation with cytochrome c and activities in cyc mutants
Authors: Liao H N , Sherman F
Published: January 2020

The cytochromes c of fungi and higher plants contain one or two residues of epsilon-N-trimethyllysine, whose biological role is unknown. A cytochrome c-specific S-adenosylmethionine:protein-sysine methyltransferase (methylase) activity was shown to be present in extracts of the bakers' yeast Saccharomyces cerevisiae, and basic kinetic properties of this enzyme are described. The specific activity of the methylase was lower in extracts of cells grown under conditions of catabolite (glucose) repression or anaerobiosis where cytochrome c levels were low, compared with cells grown under derepressed conditions where cytochrome c levels were high. During anaerobic-to-aerobic adaptation, the methylase was induced in parallel with cytochrome c, thus suggesting that the syntheses of cytochrome c and cytochrome c methylase are coordinately regulated. None of the cyc strains surveyed (cyc1, cyc2, cyc3, cyc4, cyc5, and cyc6) had diminished levels of methylase, although some of them were completely or almost completely deficient in cytochrome c.
Chemical heterogeneity of major outer membrane pore proteins of Escherichia coli
Authors: Lee D R , Schnaitman C A , Pugsley A P
Published: January 2020

Peptide mapping and isoelectric focusing were used to compare the major outer membrane pore proteins from various strains of Escherichia coli K-12, including strains carrying mutations in the nmpA, nmpB, and nmpC genes which result in the production of new membrane proteins. Proteins 1a, 1b, and 2 and the NmpA proteins each gave unique peptide and isoelectric focusing profiles, indicating that these are different polypeptides. The NmpA protein and the NmpB protein appeared to be identical by these criteria. The NmpC protein and protein 2 were nearly identical, although one different peptide was observed in comparing the proteolytic peptide maps of these proteins and there were slight differences in their isoelectric focusing profiles. Antiserum against protein 2 showed partial cross-reactivity with the NmpC protein. These results indicate that the various pore proteins of E. coli K-12 fall into four different classes.
Alteration of colonial morphology of Acholeplasma laidlawii and Acholeplasma modicum by infection with Mycoplasmatales viruses
Authors: Congdon A L , Kenny G E
Published: January 2020

Morphologically aberrant colonies resulted from the infection of Acholeplasma laidlawii with two of its three known viruses and from Acholeplasma modicum cells naturally carrying virus. The patterns of colonial alteration differed between cells infected with the two A. laidlawii viruses. Colonies derived from single cells infected with the bullet-shaped virus MV-L1 (Mycoplasmatales virus-laidlawii-1) had a radial sectoring pattern of intracolonial swellings ("blebs"), whereas cells infected with the tailed icosahedral virus MV-L3 contained bubble-like blebs. Colonies from cellsinfected with the enveloped virus MV-L2 appeared identical to those obrained from uninfected cells. Aberrant colonies contained 10(6) colony-forming units of organisms and 10(6) plaque-forming units of virus serologically identical to the infecting type, indicating that both the virus and host organism were capable of simultaneous replication. Enumeration of virus by means of counting aberrant colonies was 30-fold more sensitive than infectious center assay for MV-L1 and 1.2- to 2-fold higher for MV-L3. Furthermore, blebbed colonies plaquing with a new virus specific to A. modicum. Thus, blebbing in colonies provides a valuable marker for detection of the Mycoplasmatales viruses.
Isolation, characterization, and in vitro assembly of the tetragonally arrayed layer of Bacillus sphaericus
Authors: Hastie A T , Brinton C C
Published: January 2020

The tetragonally arranged cell wall layer (T-layer) of Bacillus sphaericus NTCC 9602 was isolated and characterized. Parallel studies were made on a spontaneous variant of the wild-type strain which had a T-layer subunit of altered molecular weight. A purification method for the T-layers was devised which involved separation of the cell walls from the cytoplasmic contents, urea dissociation of the T-layer from the cell walls, removal of soluble contaminants by differential centrifugation, and finally selective adsorption of uncleaved subunits to sacculi. The purified subunits retained the capacity to form an assembly in vitro with the same lattice parameters as that observed on whole cells or cell walls and could readsorb to the cell walls from which they had been extracted. Both the wild-type and the variant subunits behaved as single, homogeneous polypeptide chains. Carbohydrate assay and isoelectric point determinations revealed that both subunit types were acidic glycoproteins. Values obtained for thebuoyant density, isoelectric point, and extinction coefficient differed minimally; major differences were observed in the molecular weight and the characterisitc width of cylinders formed by in vitro-assembled T-layer of the wild-type and variant. Assembled T-layer was subject to alkaline or acid dissociation and in acid titration dissociated at its isoelectric point.
Effect of cyclic guanosine 3',5'-monophosphate on nitrogen fixation in Rhizobium japonicum
Authors: Lim S T , Hennecke H , Scott D B
Published: January 2020

The addition of exogenous cyclic guanosine 3',5'-monophosphate (cGMP) at a concentration of 0.1 mM to a free-living culture of Rhizobium japonicum 3I1b110 was found to completely inhibit the expression of nitrogenase activity and markedly inhibit the expression of hydrogenase and nitrate reductase activities. The effect was specific for cGMP. Experiments on the in vivo incorporation of radioactive methionine and subsequent analysis of the labeled proteins on polyacrylamide gels showed that the biosynthesis of nitrogenase polypeptides was inhibited. It appears that the time of addition of cGMP is important since the effect was only seen during the early stages of nif gene expression. The intracellular level of cGMP was found to respond to physiological changes in the cell, and there was a fall in cGMP concentrations when nitrogenase was induced. Microaerophilic-aerobic shift experiments showed that intracellular levels increased from 0.25 pmol/mg of cell protein under microaerophilic conditions to 2.6 pmol/mg of cell protein under aerobic conditions, suggesting that the cellular pool size of cGMP may be under redox control.
Transposition of Tn
7
in
Pseudomonas aeruginosa
and Isolation of
alk
::Tn
7
Mutations
Authors: Fennewald Michael A. , Shapiro James A.
Published: January 2020

Conjugal crosses with
Pseudomonas aeruginosa
donors carrying the CAM-OCT and RP4::Tn
7
plasmids result in transfer of the Tn
7
trimethoprim resistance (Tp
r
) determinant independently of RP4 markers. All Tp
r
exconjugants which lack RP4 markers have CAM-OCT genes and therefore must have received CAM-OCT::Tn
7
plasmids formed by transposition of Tn
7
from RP4::Tn
7
to CAM-OCT. Most crosses yield exconjugants carrying mutant CAM-OCT plasmids which no longer determine either camphor or alkane utilization and thus appear to carry Tn
7
inserts in the
cam
or
alk
loci, respectively. Transduction and reversion experiments indicated that at least 13 alkane-negative, camphor-positive, Tp
r
CAM-OCT::Tn
7
plasmids carry an
alk
::Tn
7
mutation. Determination of linkage between the
alk
mutation and the Tp
r
determinant of Tn
7
on these plasmids is complicated by the presence of multiple copies of the Tn
7
element in the genome. Generalized transduction will remove Tn
7
from a CAM-OCT
alk
::Tn
7
plasmid to yield
alk
+
cells which carry no Tp
r
determinant on the CAM-OCT plasmid (as shown by transfer of the plasmid to a second strain). But the transduction to
alk
+
does not remove all Tp
r
determinants from the genome of the recipient cell because the alkane-positive transductants remain trimethoprim resistant. Thus, it appears that copies of Tn
7
can accumulate in the genome of
P. aeruginosa
(CAM-OCT
alk
::Tn
7
) strains without leaving their original site. This result is consistent with transposition models that involve replication of the transposable element without excision from the original site.
Arylsulfatase in Salmonella typhimurium: detection and influence of carbon source and tyramine on its synthesis
Authors: Henderson M J , Milazzo F H
Published: January 2020

Arylsulfatase synthesis was shown to occur in Salmonella typhimurium LT2. The enzyme had a molecular weight of approximately 50,000 and was separated into five forms by isoelectrofocusing. The optimal pH for substrate hydrolysis was pH 6.7, with Michaelis constants for nitrocatechol sulfate and nitrophenyl sulfate being 4.1 and 7.9 mM, respectively. Enzyme synthesis was strongly influenced by the presence of tyramine in the growth medium. The uptake of [14C]tyramine and arylsulfatase synthesis were initiated during the second phase of a diauxie growth response, when the organism was cultured with different carbon sources. Adenosine 3',5'-cyclic monophosphoric acid enhanced the uptake of tyramine and the levels of arylsulfatase synthesized. However, the addition of glucose and glycerol to organisms actively transporting tyramine and synthesizing enzyme caused a rapid inhibition of both of these processes. This inhibition was not reversed by adding adenosine 3',5'-cyclic monophosphoric acid. The results suggest that the effect of the carbon source on tyramine transport and arylsulfatase synthesis may be explained in terms of inducer exclusion.
Negative control of octopine degradation and transfer genes of octopine Ti plasmids in Agrobacterium tumefaciens
Authors: Klapwijk P M , Schilperoort R A
Published: January 2020

The regulatory system that controls the expression of the Ti plasmid-borne octopine degradation (uad) and transfer (tra) genes in Agrobacterium tumefaciens was studied. A deletion mutant derived from the cointegrate plasmid R702::Ti-B6S3 was isolated, which was compatible with a wild-type Ti plasmid and which had retained the uad genes. By means of this mutant plasmid pAL116, it was possible to make cells diploid for the uad genes. pAL116 was introduced into Rec- strains that contained different types of regulation mutants for the uad and tra genes. The repression pattern that was found in this complementation analysis indicated that the uad and tra operons are controlled by a common repressor system. Several results indicated that there may be additional transcriptional relations between both operons. The corresponding genes of the non-tumorigenic octopine plasmid pAt-AG60 appeared to be controlled by a repressor related to that of the octopine Ti plasmid.
Spontaneous and induced rho mutants of Saccharomyces cerevisiae: patterns of loss of mitochondrial genetic markers
Authors: Heude M , Fukuhara H , Moustacchi E
Published: January 2020

The deletion which leads to spontaneous rho mutants occurs preferentially at a unique region covering genes oxi3, pho1/OII, and mit175. The frequency of loss of genetic markers in this region was significantly higher than in other regions as determined with a 15- marker system. When various mutagenic treatments were applied, this specific pattern of deletion was also observed, but it was dramatically amplified. This suggests that the basic mechanism of rho production is the same in yeast mitochondrial genomes in both spontaneous and induced mutants.
Heat Activation of
Phycomyces blakesleeanus
Spores: Thermodynamics and Effect of Alcohols, Furfural, and High Pressure
Authors: Thevelein Johan M. , Van Assche Jozef A. , Carlier Albert R. , Heremans Karel
Published: January 2020

The thermodynamic parameters for the heat activation of the sporangiospores of
Phycomyces blakesleeanus
were determined. For the apparent activation enthalpy (Δ

H
#

) a value of 1,151 kJ/mol was found, whereas a value of 3,644 J./°K·mol was calculated for the apparent activation entropy (Δ

S
#

).
n
-Alcohols (from methanol to octanol), phenethyl alcohol, and furfural lowered the activation temperature of
P. blakesleeanus
spores. The heat resistance of the spores was lowered concomitantly. The effect of the alcohols was a linear function of the concentration in the range that could be applied. When the log of the concentration needed to produce an equal shift of the activation temperature was plotted for each alochol against the log of the octanol/water partition coefficient, a straight line was obtained. The free energy of adsorption of the
n
-alcohols to their active sites was calculated to be −2,487 J/mol of CH
2
groups. Although still inconclusive, this points toward an involvement of protein in the activation process. The effect of phenethyl alcohol was similar to the effect of
n
-alcohols, but furfural produced a greater shift than would be expected from the value of its partition coefficient. When the heat activation of the spores was performed under high pressure, the activation temperature was raised by 2 to 4°K/1,000 atm. However, with pressures higher than 1,000 atm (1.013 × 10
5
kPa) the activation temperature was lowered until the pressure became lethal (more than 2,500 atm). It is known that membrane phase transition temperatures are shifted upward by about 20°K/1,000 atm and that protein conformational changes are shifted upward by 2 to 6°K/1,000 atm. Consequently, heat activation of fungal spores seems to be triggered by a protein conformational change and not by a membrane phase transition. Activation volumes of −54.1 cm
3
/mol at 38°C and −79.3 cm
2
/mol at 40°C were found for the lowering effect of high pressure on the heat activation temperature.
Ribonucleic acid polymerase mutation affecting glutamate synthase activity in and sporulation of Bacillus subtilis
Authors: Ryu J I , Takayanagi S
Published: January 2020

Spore formation of 15 rifampin-resistant (Rifr) mutants of Bacillus subtilis strain 168 was examined. As a pleiotropic effect of a Rifr mutation, glutamate synthase activity was lost in these mutants. Twelve of the 15 mutants examined formed as many spores as the parent, but the remaining 3 formed significantly fewer (1%) spores. One of the latter mutants characterized further (RF301) was blocked in its sporulation process at stage 0. Thus, it was concluded that a certain modification of ribonucleic acid polymerase may affect specifically the gene expression of glutamate synthase and also the sporulation process at the initial stage.
Extrachromosomal psi+ determinant suppresses nonsense mutations in yeast
Authors: Liebman S W , Sherman F
Published: January 2020

The extrachromosomal psi+ determinant in the yeast Saccharomyces cerevisiae enhanced the expression of Mendelian UAA suppressors by 6- to 10-fold. The psi+ determinant by itself is a weak UAA suppressor that caused the production of approximately 1% of the normal level of iso-1-cytochrome c in a strain containing the UAA mutation cycl-72.
The ends of Tn10 are not IS3
Authors: Ross D G , Grisafi P , Kleckner N , Botstein D
Published: January 2020

By heteroduplex and hybridization analysis we showed that the inverted repetition (here called IS10) at the ends of the translocatable tetracycline resistance element Tn10 is not IS3, as had previously been reported by Ptashne and Cohen (J. Bacteriol. 122:776--781, 1975). Further analysis confirmed the homology between IS3 and the alpha beta sequence of F and demonstrated that IS10 was not present in the genomes of Salmonella typhimurium LT2 or Escherichia coli K-12.
Two mutations which affect the barrier function of the Escherichia coli K-12 outer membrane
Authors: Coleman W G , Leive L
Published: January 2020

Two genetically distinct classes of novobiocin-supersensitive mutants were isolated from Escherichia coli K-12. One class, given the phenotypic name NbsA, lies at 10 min on the E. coli chromosome. The order of the genes in this region, based on transductional analyses, is proC NbsA plsA purE. The second, NbsB, lies at 80 min. The order of the genes in this region, based on transduction analyses, is xyl cysE NbsB pyrE. Both classes of mutants show increased sensitivity to hydrophobic drugs but are different: NbsA cells tend to be more sensitive to cationic agents, whereas NbsB cells show the opposite tendency. The sole detectable biochemical alteration in NbsA strain is greater than 90% reduction in the phosphate content of the lipid A region of the lipopolysaccharide. The NbsB mutation results in lipopolysaccharide that contains primarily the stereoisomer D-glycero-D-mannoheptose, rather than L-glycero-D-mannoheptose, and which contains very little of the distal sugars. Since NbsA strains have apparently normal outer membrane proteins and total cellular phospholipids, changes solely in lipopolysaccharide can increase permeability to certain hydrophobic antibiotics. Complementation studies indicate that the NbsA marker is probably allelic with acrA. In addition, the NbsB marker is genetically and phenotypically similar to the rfaD locus of Salmonella typhimurium. For this reason, the phenotypic designations NbsA and NbsB have been changed to the genotypic designations acrA and rfaD, respectively.
Chemotaxis of Salmonella typhimurium toward citrate
Authors: Kihara M , Macnab R M
Published: January 2020

Salmonella, but not Escherichia coli, was attracted to citrate, a distinction that is understandable in view of the inability of E. coli to transport tricarboxylic acids. The Salmonella response to citrate and to two previously described attractants, aspartate and malate, was mutually noncompetitive. Citrate taxis different from citrate uptake in that it did not require Na+, was constitutive, and was not repressible by glucose.
Microcalorimetric study of Escherichia coli aerobic growth: kinetics and experimental enthalpy associated with growth on succinic acid
Authors: Dermoun Z , Belaich J P
Published: January 2020

A new batch calorimeter was used to study the aerobic growth of Escherichia coli in a minimal containing a growth-limiting concentration of succinic acid. The shape of the thermograms obtained was simple when the energy source was the only growth-limiting factor and showed a stationary phase when the oxygen transfer was limiting. The experimentally determined value of the heat production during growth was found to be significantly lower than the heat of combustion of the succinic acid corrected for the assimilated-substrate fraction. An interpretation has been given to explain the difference between the experimental and the theoretical values.
Escherichia coli
Mutants Thermosensitive for Deoxyribonucleic Acid Gyrase Subunit A: Effects on Deoxyribonucleic Acid Replication, Transcription, and Bacteriophage Growth
Authors: Kreuzer Kenneth N. , Cozzarelli Nicholas R.
Published: January 2020

Temperature-sensitive
nalA
mutants of
Escherichia coli
have been used to investigate the structure and functions of deoxyribonucleic acid (DNA) gyrase. Extracts of one such mutant (
nalA43
) had thermosensitive DNA gyrase subunit A activity but normal gyrase subunit B activity, proving definitively that
nalA
is the structural gene for subunit A. Extracts of a second
nalA
(Ts) mutant (
nalA45
) had a 50-fold deficiency of gyrase subunit A activity. The residual DNA supertwisting was catalyzed by the mutant DNA gyrase rather than by a novel supertwisting enzyme. The
nalA45
(Ts) extract was also deficient in the nalidixic acid target, which is defined as the protein necessary to confer drug sensitivity to in vitro DNA replication directed by a nalidixic acid-resistant mutant extract. Thus, gyrase subunit A and the nalidixic acid target are one and the same protein, the
nalA
gene product. Shift of the
nalA43
(Ts) mutant to a nonpermissive temperature resulted in a precipitous decline in the rate of [
3
H]thymidine incorporation, demonstrating an obligatory role of the
nalA
gene product in DNA replication. The rates of incorporation of [
3
H]uridine pulses and continuously administered [
3
H]uracil were quickly reduced approximately twofold upon temperature shift of the
nalA43
(Ts) mutant, and therefore some but not all transcription requires the
nalA
gene product. The thermosensitive growth of bacteriophages φX174 and T4 in the
nalA43
(Ts) host shows that these phages depend on the host
nalA
gene product. In contrast, the growth of phage T7 was strongly inhibited by nalidixic acid but essentially unaffected by the
nalA43
(Ts) mutation. The inhibition of T7 growth by nalidixic acid was, however, eliminated by temperature inactivation of the
nal43
gene product. Therefore, nalidixic acid may block T7 growth by a corruption rather than a simple elimination of the nalidixic acid target. Possible mechanisms for such a corruption are considered, and their relevance to the puzzling dominance of drug sensitivity is discussed.
Translational regulation of polysome formation during dormancy of Physarum polycephalum
Authors: Jeffery W R
Published: January 2020

The translational activity of actively growing microplasmodia and dormant microsclerotia of Physarum polycephalum was investigated by analyzing the distribution of ribosomes in polysomes. Microplasmodial post-mitochondrial fractions contained substantial amounts of polysomes and ribosomal subunits but very few native monosomes. During the starvation period which preceded microsclerotium formation, polysome levels remained constant, whereas the subunit titer began to increase. During encystment ribosomal subunits continued to accumulate as the level of polysomes gradually decreased. Dormant microsclerotia contained a large surplus of stored ribosomal subunits but no detectable polysomes. However, incubation of microsclerotia with concentrations of cycloheximide sufficient to slow polypeptide elongation without affecting initiation caused the gradual reappearance of polysomes at the expense of the subunits. Under these conditions the percentage of subunits driven into polysomes reached values similar to those of actively growing microplasmodia. Microsclerotia returned to nutrient medium contained very low levels of polysomes during the lag period which preceded germination. These were formed with preexisting, stored messenger ribonucleic acid. During the germination period, polysome levels were markedly increased. This elevation was dependent on new ribonucleic acid transcription. It is concluded that dormant microsclerotia contain functional messenger ribonucleic acid and ribosomes which are subject to translational repression at the level of initiation.
Genetics and physiology of proline utilization in Saccharomyces cerevisiae: mutation causing constitutive enzyme expression
Authors: Brandriss M C , Magasanik B
Published: January 2020

A mutation resulting in inducer-independent expression of the proline-degradative enzymes was isolated in the yeast Saccharomyces cerevisiae. Strains carrying the mutation, put3, are partially constitutive for proline oxidase and delta 1-pyrroline-5-carboxylate dehydrogenase when grown on a medium lacking proline and are hyperinducible for both enzyme activities when grown on a proline-containing medium. put3 segregates as a single nuclear gene, is not linked to either of the presumed structural genes for proline oxidase and delta 1-pyrroline-5-carboxylate dehydrogenase, and does not affect proline transport. When heterozygous in diploid strains, put3 behaves neither fully dominant nor fully recessive. Endogenous induction by proline has been eliminated as a cause of the inducer-independent enzyme expression in the put3 mutant and the mutation is believed to be in a regulatory component of the proline-degradative pathway.
Regulated breakdown of Escherichia coli deoxyribonucleic acid during intraperiplasmic growth of Bdellovibrio bacteriovorus 109J
Authors: Rosson R A , Rittenberg S C
Published: January 2020

During growth of Bdellovibrio bacteriovorus on [2-14C]deoxythymidine-labeled Escherichia coli, approximately 30% of the radioactivity was released to the culture fluid as nucleoside monophosphates and free bases; the remainder was incorporated by the bdellovibrio. By 60 min after bdellovibrio attack, when only 10% of the E. coli deoxyribonucleic acid (DNA) had been solubilized, the substrate cell DNA was degraded to 5 X 10(5)-dalton fragments retained within the bdelloplast. Kinetic studies showed these fragments were formed as the result of sequential accumulation of single- and then double-strand cuts. DNA fragments between 2 X 10(3) and 5 X 10(5) daltons were never observed. Chloramphenicol, added at various times after initiation of bdellovibrio intraperiplasmic growth on normal or on heated E. coli, which have inactivated deoxyribonucleases, inhibited further breakdown and solubilization of substrate cell DNA. Analysis of these intraperiplasmic culture deoxyribonuclease activities showed that bdellovibrio deoxyribonucleases are synthesized while E. coli nucleases are inactivated. It is concluded that continuous and sequential synthesis of bdellovibrio deoxyribonucleases of apparently differing specificities is necessary for complete breakdown and solubilization of substrate cell DNA, and that substrate cell deoxyribonucleases are not involved in any significant way in the degradation process.
Interaction of bacteriophage K10 with its receptor, the lamB protein of Escherichia coli
Authors: Roa M
Published: January 2020

The lamB protein of Escherichia coli was initially recognized as the receptor for bacteriophage lambda. It is now shown also to constitute the receptor for phage K10. The lamB protein interacts with phage K10 in vitro, but this interaction does not lead to phage inactivation. Most lambda-resistant labB mutants are also resistant to K10, and vice versa. However, a significant proportion of the mutants resistant to one of the phages is sensitive to the other. Nineteen K10-resistant lambda-sensitive mutants have been studied. Only six of them produce a lamB protein which seems totally unimpaired in its ihe same deletion interval of the lamB gene. The corresponding region of the lamB polypeptide must be specifically involved in the interaction with phage K10. An unusual pattern of K10 host range mutants has been obtained; two calsses of such mutants could be defined, growing on two distinct classes of K10-resistant lamB mutants.
Properties and function of the proton-translocating adenosine triphosphatase of Clostridium perfringens
Authors: Hasan S M , Rosen B P
Published: January 2020

Growth of Clostridium perfringens was inhibited by compounds which dissipate or prevent the formation of electrochemical proton gradients. Membrane vesicles prepared from this organism exhibited Mg2+-dependent adenosine triphosphatase (ATPase) activity sensitive to N,N'-dicyclohexylcarbodiimide. Mg2+-ATPase activity was optimal of 50 degrees C, but no discrete pH optimum was observed. Adenosine triphosphate-dependent quenching of the fluorescence of the weak base quinacrine by everted membrane vesicles suggested that the Mg2+-ATPase is a proton pump capable of generating an electrochemical proton gradient. Adenosine triphosphate-dependent transport of Ca2+ by everted vesicles was sensitive to uncouplers and inhibitors of the Mg2+-ATPase.
Chemosensory responses of Halobacterium halobium
Authors: Schimz A , Hildebrand E
Published: January 2020

Responses of Halobacterium halobium cells to chemical stimuli have been shown by a capillary technique. Cells were attacted by D-glucose and several amino acids and repelled by phenol. Certain chemicals, such as acetate, benzoate, indole, and NiSO4, that are known to act as repellents of Escherichia coli cells served as attractants for Halobacterium. In the presence of ethionine, sensitivity to attractants was reduced. Arsenate prevented the attraction by glucose without lowering the cellular adenosine 5'-triphosphate level. The ability for chemo-accumulation toward glucose and histidine was interfered with by the formation of photosensory systems. Light-induced motor responses and chemosensory behavior toward glucose and histidine became detectable in the late stationary growth phase only. The behavior toward acetate and indole was not connected to photobehavior in that way: both substances acted as attractants already in the late log phase. Inhibition of bacteriorhodopsin synthesis by L-nicotine allowed chemo-accumulation toward glucose and histidine already in the late logarithmic phase.
Differential growth rates of Candida utilis mother and daughter cells under phased cultivation
Authors: Thomas K C , Dawson P S , Gamborg B L
Published: January 2020

The yeast Candida utilis was continuously synchronized by the phased method of cultivation with the nitrogen source as the growth-limiting nutrient. The doubling time (phasing period) of cells was 6 h. Both cell number and deoxyribonucleic acid synthesis showed a characteristic stepwise increase during the phased growth. The time of bud emergence coincided with the time of initiation of deoxyribonucleic acid synthesis. Size distribution studies combined with microscopic analysis showed that the cells expanded only during the unbudded phase of growth. Usually the cells stopped increasing in size about 30 min before bud emergence, and the arrest of the increase in cell volume coincided with the exhaustion of nitron from the medium. There was no net change in the volume of cells during the bud expansion phase of growth, suggesting that as the bud expanded, the volume of the mother portion of the cell decreased. After division the cells expanded slightly. The postdivision expansion of cells, unlike the growth before bud initiation, occurred in the absence of the growth-limiting nutrient. The newly formed daughter cells were smaller than the mother cells and expanded at a faster rate, so that both types of cells reached maximum size at the same time. Possible reasons for the different rates of expansion of mother and daughter cells are discussed.
Transposition of Tn904 encoding streptomycin resistance into the octopine Ti plasmid of Agrobacterium tumefaciens
Authors: Klapwijk P M , van Breukelen J , Korevaar K , Ooms G , Schilperoort R A
Published: January 2020

A transfer-deficient derivative of plasmid RP1-pMG1 was isolated after insertion of Mu cts62. The Tra- R plasmid was used to donate Tn904, encoding streptomycin resistance, to Ti plasmid pAL102 harbored by Agrobacterium tumefaciens Ach5. Under conditions promoting high Ti transfer frequencies, 155 strains were isolated in which the streptomycin marker coupled with Ti plasmid in further transfer experiments. These isolates represent stable insertions of Tn904 into the Ti plasmid. In addition, 19 strains were isolated in which the insertion of Tn904 was apparently unstable. The frequency of stable Tn904 transpositions was estimated to be 3 x 10(4-) per transferred Ti plasmid. Evidence was obtained that Tn904 readily may transpose from the Ti plasmid into the bacterial chromosome. The strains carrying Ti plasmids with stable insertions were characterized with respect to virulence, octopine degradation, octopine synthesis in induced tumors, and Ti plasmid transfer. Thirteen of the strains were found to be affected in tumor-inducing ability.
Periplasmic maltose-binding protein confers specificity on the outer membrane maltose pore of Escherichia coli
Authors: Heuzenroeder M W , Reeves P
Published: January 2020

ompB mutants of Escherichia coli K-12 are markedly deficient in porin in their outer membrane. This results in a decreased rate of uptake for many substrates: the maltose pore (lambda receptor) can in some circumstances, in the absence of the periplasmic maltose-binding protein, compensate for the consequent defects in permeability to lactose, mannitol, glycylglycyl-L-valine, and tri-L-ornithine. It is postulated that the maltose-binding protein associates with the maltose pore and confers on it the specificity for maltose, and that the absence of the maltose-binding protein leaves the pore open and results in enhanced transmembrane diffusion of molecules other than maltose. This paper presents evidence to support this hypothesis.
Cell-cycle-specific inhibition by chloramphenicol of septum fromation and cell division in synchronized cells of Bacillus subtilis
Authors: Miyakawa Y , Komano T , Maruyama Y
Published: January 2020

The relationship between protein synthesis and processes of cell division was studied by using synchronized cells of Bacillus subtilis 168. The addition of chloramphenicol at the beginning of synchronous growth prevented septum formation and cell division, suggesting the requirement of protein synthesis for the processes of cell division. Experiments in which the drug was added to the cells at different cell ages showed that the protein synthesis required for the initiation of septum formation was completed at about 15 min and that the protein synthesis required for cell division was completed at about 45 min. By interpreting the result from the concept of the transition point for protein synthesis, it was suggested that the processes of cell division in B. subtilis require at least two kinds of protein molecules which are synthesized at distinct stages in the cell cycle. This was supported by the result of an experiment in which starvation and the readdition of a required amino acid to exponentially growing cells induced two steps of synchronous cell division. Further, the two transition points are in agreement with the estimations obtained by residual division after the inhibition of protein synthesis in asynchronous cells. The relationship of the timing between the completion of chromosome replication and the two transition points was also studied.
Ammonia assimilation and glutamate formation in the anaerobe Selenomonas ruminantium
Authors: Smith C J , Hespell R B , Bryant M P
Published: January 2020

Selenomonas ruminantium was found to possess two pathways for NH4+ assimilation that resulted in net glutamate synthesis. One pathway fixed NH4+ through the action of an NADPH-linked glutamate dehydrogenase (GDH). Maximal GDH activity required KCl (about 0.48 M), but a variety of monovalent salts could replace KCl. Complete substrate saturation of the enzyme by NH4+ did not occur, and apparent Km values of 6.7 and 23 mM were estimated. Also, an NADH-linked GDH activity was observed but was not stimulated by KCl. Cells grown in media containing non-growth-rate-limiting concentrations of NH4+ had the highest levels of GDH activity. The second pathway fixed NH4+ into the amide of glutamine by an ATP-dependent glutamine synthetase (GS). The GS did not display gamma-glutamyl transferase activity, and no evidence for an adenylylation/deadenylylation control mechanism was detected. GS activity was highest in cells grown under nitrogen limitation. Net glutamate synthesis from glutamine was effected by glutamate synthase activity (GOGAT). The GOGAT activity was reductant dependent, and maximal activity occurred with dithionite-reduced methyl viologen as the source of electrons, although NADPH or NADH could partially replace this artificial donor system. Flavin adenine dinucleotide, flavin mononucleotide, or ferredoxin could not replace methyl viologen. GOGAT activity was maximal in cells grown with NH4+ as sole nitrogen source and decreased in media containing Casamino Acids.
Localization of Enterobacterial Common Antigen: Immunogenic and Nonimmunogenic Enterobacterial Common Antigen-Containing
Escherichia coli
Authors: Rinno J. , Golecki J. R. , Mayer H.
Published: January 2020

In rabbits immunized with intact bacteria, the immune response to the enterobacterial common antigen (ECA) predominantly consists of the production of immunoglobulin M antibodies. This is not dependent on whether the animals are immunized for a short (2 weeks) or a long (3 months) period of time. The highest ECA-specific immunoglobulin G titers were observed after a short immunization with living bacteria. ECA-specific antisera were obtained by absorption with appropriate ECA-negative mutants. The absorbed antisera were then separated on Sephadex G-200. The resulting immunoglobulin G fractions were conjugated to ferritin by glutardialdehyde and used to visualize the distribution of ECA in
E. coli
. Bacterial strains either possessing the immunogenic form of ECA (F470, 2387) or solely the nonimmunogenic form (F614) or being devoid of both (ECA-negative mutants F1283 and F1327) were labeled with the conjugates. Freezeetchings of ferritin-labeled strains showed a dense labeling of the outer membrane in case of ECA-immunogenic strains, an essentially weaker labeling of the non-immunogenic ECA mutant and, as expected, no labeling of ECA-negative mutants. Comparable results were obtained with the indirect immunofluorescence technique: the whole cell envelope of strain F470 showed a brilliant fluorescence, whereas a much lesser, spotty distribution of fluorescence was noted with strain F614 and none at all was noted with the ECA-negative strains. These data show that ECA is localized in the outer membrane of ECA-containing strains and further demonstrate that there is more in the immunogenic strains than in the nonimmunogenic ones.
Infection and nodulation of clover by nonmotile Rhizobium trifolii
Authors: Napoli C , Albersheim P
Published: January 2020

Nonmotile mutants of Rhizobium trifolii were isolated to determine whether bacterial motility is required for the infection and nodulation of clover. The nonmotile mutants were screened for their ability to infect and nodulate clover seedlings in Fahraeus glass slide assemblies, plastic growth pouches, and vermiculite-sand-filled clay pots. In each system, the nonmotile mutants were able to infect and nodulate clover.