Growth Requirements of Virus-Resistant Mutants of Escherichia Coli Strain "B"

Regulation of thymidine metabolism in Escherichia coli K-12: studies on the inducer and the coordinateness of induction of the enzymes

A study was made of the regulation of three enzymes that act sequentially in the metabolism of thymidine in Escherichia coli K-12. Under a variety of conditions, two of the enzymes, thymidine phosphorylase and deoxyribose-5-phosphate aldolase, were found to be synthesized coordinately. However, the third enzyme, phosphodeoxyribomutase, was synthesized noncoordinately with the other two enzymes under the same conditions. In addition, the mutase could be fully induced, whereas basal levels of the phosphorylase and the aldolase were maintained. These findings indicate that two operons comprise the genes concerned with the reversible pathway leading from thymidine to acetaldehyde and glyceraldehyde-3-phosphate. In addition to thymidine, it was found that acetaldehyde was an external inducer of these enzymes. The results of induction experiments performed on wild-type cells and mutants defective in the mutase or the aldolase, with thymidine or acetaldehyde as exogenous inducers, strongly suggest that deoxyribose-5-phosphate is more proximal to the intracellular inducer than is thymidine, deoxyribose-1-phosphate, or acetaldehyde.

Effect of colicin E3 upon the 30S ribosomal subunit of Escherichia coli

The properties of 30S ribosomal subunits from untreated and from colicin E3-treated (E3-30S) bacteria have been compared. Polyacrylamide gel electrophoresis of ribosomal proteins revealed no difference, but several studies indicated that the 16S RNA from E3-30S particles was modified. E3-16S RNA showed slightly increased resistance to heat-induced degradation and had a reduced (15 S) sedimentation coefficient on sucrose gradients. Fingerprint analyses of E3-16S RNA revealed that the 3'-terminus of the molecule had been deleted. It was concluded that a primary effect of colicin E3 is the activation of a highly specific RNase that degrades 30S ribosomal RNA in situ, and that the resulting fragment(s) are probably retained within the 30S particle.

Regulation of thymidine metabolism in Escherichia coli K-12: evidence that at least two operons control the degradation of thymidine

In Escherichia coli K-12, the rise in activity of thymidine phosphorylase, phosphodeoxyribomutase, and deoxyribose-5-phosphate aldolase caused by exogenous thymidine is dependent on the synthesis of new enzyme protein. Phosphodeoxyribomutase is induced by the purine ribonucleosides adenosine and guanosine, whereas the other two enzymes are not. The mutase activity induced by thymidine and by the purine ribonucleosides has been shown to be the same enzyme by four different criteria. This independent induction of phosphodeoxyribomutase suggests that the gene for this enzyme is in an operon different from the one that may contain the genes for thymidine phosphorylase and deoxyribose-5-phosphate aldolase.

Replication and repair of DNA in cells of Escherichia coli treated with toluene

DNA synthesis has been studied in Escherichia coli cells made permeable to nucleotides by treatment with toluene. Replicative synthesis, as distinguished from repair synthesis, occurs at a rate comparable to that observed in vivo; it is dependent on the presence of all four deoxyribonucleoside triphosphates, but does not require exogenous DNA; and it is stimulated by ATP. Furthermore, replicative synthesis can be abolished at the restrictive temperature in DNA temperature-sensitive mutants. N-ethylmaleimide completely inhibits this type of synthesis, whereas it does not inhibit repair synthesis. Repair synthesis further differs from replicative synthesis in the following points: it does not require ATP; it persists at the restrictive temperature in DNA temperature-sensitive mutants; it can be induced by endogenous or exogenous nuclease activity; and its demonstration requires a Pol(+) strain.

Regulation of thymidine metabolism in Escherichia coli K-12: optimal conditions for the assay of 1,5-phosphodeoxyribomutase in ultrasonic extracts

Assay conditions have been established which allow maximum expression of phosphodeoxyribomutase activity in ultrasonic extracts of Escherichia coli K-12. The enzyme requires 2-mercaptoethanol, manganous ions, and glucose 1,6-diphosphate for optimal activity. When cells are grown in minimal medium with glycerol as the carbon source and supplemented with 10(-3)m thymidine, phosphodeoxyribomutase is induced three- to four-fold. Cell pellets may be frozen for 24 hr before sonic disruption without loss of enzyme activity. The assay is highly reproducible.

Genetic analysis of a large-cell, radiation-resistant strain of Escherichia coli

A genetic analysis of Escherichia coli P6, a large-cell, radiation-resistant strain of E. coli, established that it originated as the result of a mutational event. The gene responsible for the complex P6 phenotype was located at 61 +/- 0.5 min on the E. coli linkage map. The close resemblance of conjugal and transductional recombinants to one or the other parent without indication of an intermediate class suggests that only a single gene may be involved.

The inhibition of ribonucleic acid synthesis by the thiol-oxidizing agent, diamide, in Escherichia coli

The thiol-oxidizing agent, diamide, has been used to convert glutathione to glutathione disulfide within the cells of a stringent strain of Escherichia coli (CP 78), leading to a cessation of 14C-leucine incorporation (protein synthesis) and 3H-uracil incorporation (RNA synthesis). Parallel experiments with an isogenic relaxed strain (CP 79) gave similar results, providing evidence that glutathione is closely linked to RNA synthesis indepently of the link previously shown to protein synthesis.

Effect of low level X radiation on the antigenicity of Escherichia coli

The biologic effects of low level X radiation (10 to 1,000 rads) were investigated by studying alterations in antigenicity of Escherichia coli. Antigen-antibody reactions were studied by immunodiffusion and immunoelectrophoresis to measure subtle changes to the radiation. A gradual change was observed in antigen-antibody patterns through the various levels of radiation.

Amino acid control over deoxyribonucleic acid synthesis in Escherichia coli infected with T-even bacteriophage

Starvation for a required amino acid of normal or RC(str)Escherichia coli infected with T-even phages arrests further synthesis of phage deoxyribonucleic acid (DNA). This amino acid control over phage DNA synthesis does not occur in RC(rel)E. coli mutants. Heat inactivation of a temperature-sensitive aminoacyl-transfer ribonucleic acid (RNA) synthetase similarly causes an arrest of phage DNA synthesis in infected cells of RC(str) phenotype but not in cells of RC(rel) phenotype. Inhibition of phage DNA synthesis in amino acid-starved RC(str) host cells can be reversed by addition of chloramphenicol to the culture. Thus, the general features of amino acid control over T-even phage DNA synthesis are entirely analogous to those known for amino acid control over net RNA synthesis of uninfected bacteria. This analogy shows that the bacterial rel locus controls a wider range of macromolecular syntheses than had been previously thought.

Effect of the thiol-oxidizing agent diamide on the growth of Escherichia coli

Oxidation of glutathione within Escherichia coli cells by diamide, (CH(3))(2)NCON=NCON(CH(3))(2), stops growth but does not cause cell death. Normal growth rates are resumed after periods which vary in length according to the diamide concentration. Consumption of excess reagent with added glutathione quickly reverses the inhibition. Another thiol-oxidizing agent, azoester, C(6)H(5)N=NCOOCH(3), causes lysis.

In vivo suppression of coding associated with bacteriophage-induced S-adenosylmethionine hydrolase

The methylation of ribosomal and transfer ribonucleic acid (RNA) synthesized after the induction of a hydrolase for S-adenosylmethionine by phage T3 infection is reducible to 50% of the methylation of RNA in uninfected cells. Hypomethylated ribosomal RNA is found in 70S particles that dissociate in 100 mum Mg(++) to yield only 30S and 50S subunits. By this criterion, the omitted methyl groups apparently are not required for ribosomal maturation or stability. The rate of production of alkaline phosphatase in a phosphatase amber mutant was examined after phage infection in the presence and in the absence of streptomycin to determine the effect on the translation process consequent to S-adenosyl-l-methionine (SAM) hydrolase induction. Significant increases in the rates of phosphatase production were found when ultraviolet-inactivated T3 or streptomycin was added. The effects were cumulative when the cells were treated with both bacteriophage and the drug. Ultraviolet-inactivated T7, a phage closely related to T3 but which does not produce the SAM hydrolase, did not enhance the rate of alkaline phosphatase production. We suggest that the production of SAM hydrolase affects the stability of the translation process by the observed hypomethylation or by mechanisms concerning polyamine metabolism.

Catabolite inhibition: a general phenomenon in the control of carbohydrate utilization

When Escherichia coli is grown in synthetic medium with radioactive galactose or lactose as the carbon source, the addition of glucose rapidly inhibited utilization of the radioactive substrate, whether the formation of (14)CO(2) or acid-insoluble products was measured. The inhibition was reversed after the removal of glucose. Experiments with mutants blocked in subsequent steps of galactose and lactose metabolism demonstrated that the inhibition occurs prior to the formation of the first metabolic product. The utilization of a variety of sugars, including maltose, lactose, mannose, galactose, l-arabinose, xylose, and glycerol was inhibited by glucose. Of a number of carbohydrates tested as potential inhibitors, only glucose and, to a lesser extent, glucose-6-phosphate (G-6-P) were capable of inhibiting the utilization of all of the substrates. Glucose did not inhibit G-6-P utilization but G-6-P inhibited glucose utilization. With all substrates, except glycerol, there was a delay before the onset of inhibition by G-6-P. We conclude that E. coli has a general regulatory mechanism, termed catabolite inhibition, which controls the activity of early reactions in carbohydrate metabolism, allowing certain substrates to be utilized preferentially.

Ribonucleic acid synthesis and glutamate excretion in Escherichia coli

Cultures of Escherichia coli excreted glutamate into the medium when protein synthesis was blocked in RC(rel) strains or when it was blocked with chloramphenicol in either RC(str) or RC(rel) strains. Both of these conditions resulted in continued ribonucleic acid (RNA) synthesis in the absence of protein synthesis. Glutamate was also excreted by both RC(str) and RC(rel) strains when RNA synthesis was inhibited by uracil starvation or by treatment with actinomycin D. It is proposed that, in each of these cases, glutamate excretion resulted from an increase in the permeability of the cell membrane.

Induction by oxygen of respiration and phosphorylation of anaerobically grown Escherichia coli

The changes occurring in the respiratory enzymes of anaerobically grown Escherichia coli strain B and E. coli 15 T(-)A(-)U(-)bar during exposure to oxygen were studied. Reduced nicotinamide adenine dinucleotide (NADH) oxidase activity reached its peak soon after O(2) exposure; cytochrome content and succinate oxidase activity increased more slowly, and these increases paralleled each other. The activities of isocitrate and malate dehydrogenases also increased, but the increase was less than that of the succinate and NADH oxidases; exposure to O(2) had no effect on the succinate and NADH dehydrogenase activities. On the other hand, the glycolytic activity decreased slowly after O(2) exposure. The incorporation of (32)P into acid-soluble organic phosphate esters paralleled the respiratory rate during the first 60 min after O(2) exposure, but continued to increase after the respiration reached a plateau. The sensitivity of (32)P incorporation to the uncoupler carbonyl cyanide m-chlorophenylhydrazone also increased with time. The observed relationship between the development of the respiratory chain and the energy-conserving mechanism during O(2) exposure is discussed. Synthesis of the respiratory enzymes upon exposure to oxygen was dependent on concomitant protein and ribonucleic acid synthesis but not on deoxyribonucleic acid synthesis.

Electronically controlled continuous culture device

A photocell-controlled continuous culture device, a Nephelostat, is described that maintains a wide variety of cultures of microorganisms in balanced growth. This Nephelostat controls concentrations of bacteria within +/-3% over a cell concentration range of 10(6) to 10(9) cells per ml. Growth rates are recorded so that changes in the growth rate are observed over small increments of time. Spontaneous and caffeine-induced mutation rates of two strains of Escherichia coli were compared under Nephelostat and chemostat conditions.

The ultraviolet photochemistry and photobiology of vegetative cells and spores of Bacillus megaterium

The ultraviolet (UV) photochemistry and photobiology of spores and vegetative cells of Bacillus megaterium have been studied. The response of vegetative cells of B. megaterium appears qualitatively similar to those of Escherichia coli, Micrococcus radiodurans, and Bacillus subtilis with respect to photoproduct formation and repair mechanisms. UV irradiation, however, does not produce cyclobutane-type thymine dimers in the DNA of spores, although other thymine photo-products are produced. The photoproducts do not disappear after photoreactivation, but they are eliminated from the DNA by a dark-repair mechanism different from that found for dimers in vegetative cells. Irradiations performed at three wavelengths produce the same amounts of spore photoproduct and give the same survival curves. Variation of the sporulation medium before irradiation results in comparable alterations in the rate of spore photoproduct production and in survival.

Genetic basis of colicin E susceptibility in Escherichia coli. I. Isolation and properties of refractory mutants and the preliminary mapping of their mutations

Colicin E-resistant mutants were isolated in Escherichia coli K-12 which, although still apparently possessing the E receptor and adsorbing colicin, were nevertheless insensitive (refractory) to its effect. Eight phenotypic groups were obtained, but some mutants from three of these groups were all shown to map at gal, whereas a second refractory locus, giving resistance to E1 alone, mapped close to thy. It is suggested that the successful fixation of any of the three distinct colicins of group E may involve a dual role for the cell surface "receptor," the first for the binding of the protein and the second for the correct orientation of the bound molecule relative to the cytoplasmic membrane. The majority of the refractory mutants isolated may derive from changes in components concerned with the second of these receptor functions. Two groups of mutants, however, refractory to only E1 or E2, probably reflect changes in the intracellular transmission systems which specifically mediate the effects of these two colicins, the changes not allowing transmission through the cytoplasmic membrane to the respective targets of the colicins. The E1 adsorption site was shown to be distinct from that for E2 and E3, indicating an early separation of the colicin E transmission systems.

Role of the galactose pathway in the regulation of beta-galactosidase

Paigen, Kenneth (Roswell Park Memorial Institute, Buffalo, N.Y.). Role of the galactose pathway in the regulation of beta-galactosidase. J. Bacteriol. 92:1394-1403. 1966.-Galactose and its metabolites, galactose-1-phosphate, uridine diphosphogalactose, and uridine diphosphoglucose, as well as metabolites derived from uridine diphosphoglucose, were tested for their role in the regulation of beta-galactosidase. In cultures of wild-type Escherichia coli strains K-12 and B, exogenous galactose was no more effective as a repressor than were other carbon sources. Exogenous galactose also did not repress beta-galactosidase when added to mutants which can accumulate intracellular galactose or galactose-1-phosphate, indicating that these compounds do not repress. In such strains, repression of beta-galactosidase formation did occur if galactose was added in the presence of another metabolizable carbon source. This repression is presumably a consequence of the growth inhibition which follows the accumulation of these compounds, and the general catabolite repression which develops during growth inhibition. Exogenous galactose did repress beta-galactosidase in a mutant which accumulates uridine diphosphogalactose. This appears to result from a combination of several factors. These include a general inhibition of protein synthesis through depletion of the uridine triphosphate pool, catabolite inhibition as a consequence of growth inhibition, as well as a specific inhibition of beta-galactosidase formation. Glucose repression of beta-galactosidase was normal in a mutant strain blocked in the formation of uridine diphosphoglucose from uridine triphosphate and glucose-1-phosphate, indicating that neither uridine diphosphoglucose nor any compound uniquely derived from it functions as the hypothetical catabolite repressor. It is concluded that at least two separate mechanisms exist for the endogenous repression of beta-galactosidase in E. coli. One is exerted by uridine diphosphogalactose or its metabolic product; the other, by the generalized catabolite repressor which is still formed in strains unable to make uridine diphosphogalactose or uridine diphosphoglucose.

Frequency of occurrence of native hapten among enterobacterial species

Anacker, R. L. (Rocky Mountain Laboratory, Hamilton, Mont.), W. D. Bickel, W. T. Haskins, K. C. Milner, E. Ribi, and J. A. Rudbach. Frequency of occurrence of native hapten among enterobacterial species. J. Bacteriol. 91:1427-1433. 1966.-Smooth cultures of representative Enterobacteriaceae were screened for the presence of native hapten, a substance previously extracted with trichloroacetic acid from the protoplasmic fraction of one strain each of Escherichia coli O111:B4 and O113. Trichloroacetic acid extracts of protoplasmic fractions of the cells were analyzed for chemical composition, for constituent sugars by paper chromatography, for immunochemical relationship to endotoxin purified by gel filtration, for sedimentation behavior, and for pyrogenicity in rabbits and lethal toxicity in chick embryos. Extracts from two of three additional strains of E. coli O113, all five additional strains of E. coli O111:B4, and one strain each of E. coli O26:B6 and O55:B5 were similar to previously described native hapten in chemical composition, sedimentation properties (S(20,w), 3.7 to 5.2), biological potency (usually less than 0.1% that of corresponding endotoxin), and immunochemical relationship to endotoxin. Extracts of one strain each of E. coli O127:B8, Serratia marcescens, Citrobacter freundii, Salmonella enteritidis, and of two lipopolysaccharide-deficient mutants of S. enteritidis differed from typical native hapten. The biosynthetic relationship of native hapten to endotoxin has not yet been revealed.

Phenomenon of transient repression in Escherichia coli

Paigen, Kenneth (Roswell Park Memorial Institute, Buffalo, N.Y.). Phenomenon of transient repression in Escherichia coli. J. Bacteriol. 91:1201-1209. 1966.-A family of mutants has been obtained in Escherichia coli K-12 in which beta-galactosidase is not inducible for approximately one cell generation after the cells are transferred to glucose from other carbon sources. After that period; the enzyme can be induced at the level appropriate to glucose-grown cultures of the parent cells. Among a wide variety of carbon sources, the only one capable of eliciting a state of transient repression is glucose. Conversely, transient repression occurs when cells are transferred to glucose from any of a variety of other carbon sources. The only exceptions to this so far discovered are lactose, gluconate, and xylose. Susceptibility to transient repression in mutants can also be induced in glucose-grown cells by a period of starvation. Mutant cells which have become susceptible to transient repression lose susceptibility in the presence of glucose only when they are under conditions which permit active protein synthesis. The presence of an inducer of beta-galactosidase is not required during this time, nor does pre-induction for beta-galactosidase diminish the susceptibility of mutants. At least two other catabolite repression-sensitive enzymes (galactokinase and tryptophanase) are also sensitive to transient repression, and the two phenomena are probably related. The absolute specificity of glucose and the pattern of response seen after growth in different carbon sources suggest that the endogenous metabolite which produces these repressions is far more readily derived from glucose in metabolism than it is from any other exogenous carbon source.

Quantitative specific antigen determination using fluorescent antibody

A technique is described for the quantitation of a specific protein in the presence of other proteins. The application of this method to the assay of bacteriophage T(2) coat protein is presented and discussed.

EFFECT OF CHELATING AGENTS ON THE GROWTH OF ESCHERICHIA COLI IN SEAWATER

Jones, Galen E. (Scripps Institution of Oceanography, University of California, La Jolla). Effect of chelating agents on the growth of Escherichia coli in seawater. J. Bacteriol. 87: 483–499. 1964.— Escherichia coli did not grow at 37 C, or grew only after a prolonged lag phase in filter-sterilized basal seawater medium (synthetic or natural seawater supplemented with glucose, NH 4 Cl, and K 2 HPO 4 ). When this basal medium was enriched with 0.01% or less organic matter, such as casein hydrolysate, peptone, or yeast extract, growth always occurred after a short lag phase. Adding 10 −5 m cysteine or autoclaving the seawater gave a similar effect. A variety of organic chelating agents (histidine, glycine, methionine, glycylglycine, 8-hydroxyquinoline, thioglycolic acid, o -phenanthroline, disodium ethylenediaminetetraacetic acid, etc.) reversed the toxicity of filter-sterilized basal seawater medium in concentrations predictable from stability constants. Even metal-complexing agents such as Na 2 S 2 O 3 , Na 2 S, and NaCN in appropriate concentrations reversed toxicity. The quality of the distilled water and the treatment of glassware had a significant effect on the growth of E. coli in basal seawater medium. It was concluded that iodate is probably not the toxic substance for E. coli in seawater, since relatively high concentrations were stimulatory. The inhibition resulting from the individual salts of synthetic seawater was proportional to their concentration; NaCl was most inhibitory. This toxicity is believed to be derived from trace impurities in the reagent-grade chemicals used to prepare synthetic seawater. Evidence was also found for the toxicity of heavy metals in natural seawater. Heavy metals in seawater appear to inhibit growth but not respiration.

INFLUENCE OF PHENYLALANINE ANALOGUES UPON BACTERIAL ACCUMULATION AND INCORPORATION OF PHENYLALANINE

Conway , T. W. (The University of Texas, Austin), E. M. Lansford, Jr., and W. Shive . Influence of phenylalanine analogues upon bacterial accumulation and incorporation of phenylalanine. J. Bacteriol. 85: 141–149. 1963.—Phenylalanine accumulation and its relation to phenylalanine incorporation into trichloroacetic acid-insoluble material in Escherichia coli 9723 were studied with a variety of structural analogues of phenylalanine. Inhibition of phenylalanine-C 14 incorporation was exerted by analogues only when their concentration was sufficient to prevent the formation of 85 to 90% of the accumulated intracellular phenylalanine “pool,” indicating that less than about 15% of the “free amino acid pool” of phenylalanine is essential for maintaining a normal rate of incorporation of phenylalanine into protein. Although certain analogues having high activity in inhibiting accumulation of phenylalanine showed low activity in preventing incorporation, no analogue was found that solely prevented accumulation.