Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A purification and some properties of proteinase A from yeast are described. A specific macromolecular inhibitor of proteinase A from yeast cytosol has been isolated and shown to be a protein (molecular weight 7,700) consisting of a majority of polar amino acids. Proline, arginine, cysteine and tryptophan were not detected in the inhibitor. Possible biological functions of proteinase A and the proteinase A-inhibitor (and of other yeast proteinases and their inhibitors) in the following processes are discussed: general protein turnover, catabolite inactivation of enzymes, enzyme degradation at starvation and at transition to spore formation, and activation of pre-enzymes and precursor proteins by limited proteolysis.
 ...
PMID:Characteristics and functions of proteinase A and its inhibitors in yeast. 2 96

When treated with chloramphenicol, Escherichia coli 15T minus produces two new species (IV and V) of transfer ribonucleic acid specific for phenylalanine in addition to the major normal species (II) and two minor normal species (I and III), which are seen as distinct components upon fractionation by chromatography on columns of benzoylated diethylaminoethyl-cellulose. Species IV is produced when cells are grown in iron-deficient medium and is, therefore, probably deficient in the 2-methylthio modification of N-6-(delta-2-isopentenyl) adenosine. A new minor species (Va) also appears under those conditions. All of the new components elute earlier than the major normal species. Addition of chloramphenicol to iron-deficient cells leads to the production of species V, and that production is blocked by rifampin, as is the production of species IV. Thus, species IV and V appear to be transcriptional products. Although E. coli 15T minus appears to be rel plus, starvation for methionine or cysteine leads to the accumulation of species IV (without addition of chloramphenicol); rifampin blocks the accumulation. Species V is still produced on addition of chloramphenicol to starved cultures. Starvation for arginine or tryptophan does not alter the chromatographic profile from the normal case. Treatment with permanganate indicates that species II and IV contain isopentenyladenosine but that species V does not. Species V appears to be deficient in both isopentenyl and methylthio modifications of adenosine and perhaps at least one other modification, because removing the isopentenyl moiety from adenosine does not convert species IV into species V, but converts it into species Va. A precursor relationship among species V, VI, and II is suggested by following the chromatographic profile of phenylalanine transfer ribonucleic acid during recovery of E. coli from treatment with chloramphenicol; the various species increase and decrease in a sequential manner.
 ...
PMID:Precursor relationship of phenylalanine transfer ribonucleic acid from Escherichia coli treated with chloramphenicol or starved for iron, methionine, or cysteine. 4 64

The bleomycins are antitumor agents composed of various cationic amides of a common inactive bleomycinic acid. At 1 mug/ml at 37 degrees, the naturally occurring spermidine derivative of bleomycin (A5) was far more lethal to Escherichia coli than were several other bleomycins tested. An exponential loss of viability was produced for 2 hr in various strains of E. coli growing in a synthetic medium. In the stringent E. coli, strain 15 TAU (thymine-arginine-uracil) rel A+ (arginine), withholding thymine did not affect the rate of killing. However, uracil starvation completely blocked killing by the antibiotic. Arginine deprival partially inhibited bleomycin killing in the stringent cell but had little effect on the lethality of the antibiotic in a relaxed isogenic strain actively synthesizing RNA. Similar results were obtained with another isogenic pair, stringent CP78 and relaxed CP79. Thus, the lethality of the antitumor agent, bleomycin, which is reported to produce breaks in bacterial and animal cell DNA in vivo and in vitro appeared totally dependent on RNA synthesis in E. coli. Nevertheless, chloramphenicol, which blocks protein synthesis and relaxes RNA synthesis in the stringent strains, also significantly inhibited the lethal action of the antibiotic, reducing the exponential rate of killing.
 ...
PMID:Synthesis and the lethality of bleomycin in bacteria. 5 23

A 1-mg/ml amount of threonine (8.4 mM) inhibited growth and sporulation of Bacillus subtilis 168. Inhibition of sporulation was efficiently reversed by valine and less efficiently by pyruvate, arginine, glutamine, and isoleucine. Inhibition of vegetative growth was reversed by asparate and glutamate as well as by valine, arginine, or glutamine. Cells in minimal growth medium were inhibited only transiently by very high concentrations of threonine, whereas inhibition of sporulation was permanent. Addition of threonine prevented the normal increase in alkaline phosphatase and reduced the production of extracellular protease by about 50%, suggesting that threonine blocked the sporulation process relatively early. 2-Ketobutyrate was able to mimic the effect of threonine on sporulation. Sporulation in a strain selected for resistance to azaleucine was partially resistant. Seventy-five percent of the mutants selected for the ability to grow vegetatively in the presence of high threonine concentrations were found to be simultaneously isoleucine auxotrophs. In at least one of these mutants, the threonine resistance phenotpye could not be dissociated from the isoleucine requirement by transformation. This mutation was closely linked to a known ilvA mutation (recombination index, 0.16). This strain also had reduced intracellular threonine deaminase activity. These results suggest that threonine inhibits B. subtilis by causing valine starvation.
 ...
PMID:Inhibition of Bacillus subtilis growth and sporulation by threonine. 10 59

Flagellin, the protomeric subunit of bacterial flagella, contains no cysteine. We have detected the incorporation of trace quantities of 35S-cysteine into flagellin, highly purified and then resolved by SDS polyacrylamide gel electrophoresis, to measure mistranslation in vivo. Under normal conditions, this value is about 6 X 10(-4) pmoles cysteine per pmole flagellin. This value is greatly increased during growth in low concentrations of streptomycin and neomycin, antibiotics which are known to stimulate misreading in vitro. Of the specific types of misreading which streptomycin stimulates in vitro, only misreading of the CGU and CGC arginine codons could give rise to illegitimate incorporation of cysteine. In agreement, partial arginine starvation increases the incorporation of 35S-cysteine into flagellin in a relA- mutant, with or without streptomycin, but has no such effect in its isogenic relA+ partner- Assuming from these results that 35S-cysteine incorporation into flagellin reflects misreading of CGU/C coda, we deduce a misreading probability per codon in the range of 10(-4).
 ...
PMID:Mistranslation in E. coli. 13 85

The pools of arginine and ornithine rapidly disappear during nitrogen starvation of Neurospora crassa. Much of this disappearance can be accounted for by degradation catalyzed by preexisting catabolic enzymes. Purine degradation is also initiated by nitrogen metabolic stress. Mobilization of these compounds into degradative reactions does not appear to be a general response to nutritional stress since neither carbon starvation nor inhibition of protein synthesis elicits this response. It is suggested that nitrogen starvation may specifically alter the distribution of arginine and ornithine between vesicles and cytosol. This would be sufficient to initiate and maintain their degradation. These result suggest that compartmentation of amino acids provides a metabolic reserve to be utilized during periods of specific nutritional stress.
 ...
PMID:Mobilization of sequestered metabolities into degradative reactions by nutritional stress in Neurospora. 15 15

Repression of biosynthetic enzyme synthesis in Pseudomonas putida is incomplete even when the bacteria are growing in a nutritionally complex environment. The synthesis of four of the enzymes of the arginine biosynthetic pathway (N-acetyl-alpha-glutamokinase/N-acetylglutamate-gamma-semialdehyde dehydrogenase, ornithine carbamoyltransferase and acetylornithine-delta-transaminase) could be repressed and derepressed, but the maximum difference observed between repressed and derepressed levels for any enzyme of the pathway was only 5-fold (for ornithine carbamoyltransferase). No repression of five enzymes of the pyrimidine biosynthetic pathway (aspartate carbamoyltransferase, dihydro-orotase, dihydro-orotate dehydrogenase, orotidine-5'-phosphate pyrophosphorylase and orotidine-5'-phosphate decarboxylase) could be detected on addition of pyrimidines to minimal asparagine cultures of P. putida A90, but a 1-5- to 2-fold degree of derepression was found following pyrimidine starvation of pyrimidine auxotrophic mutants of P. putida A90. Aspartate carbamoyltransferase in crude extracts of P. putida A90 was inhibited in vitro by (in order of efficiency) pyrophosphate, CTP, UTP and ATP, at limiting but not at saturating concentrations of carbamoyl phosphate.
 ...
PMID:Regulation of arginine and pyrimidine biosynthesis in Pseudomonas putida. 17 12

The phenotype of certain mutations in pyrA, the gene encoding carbamylphosphate synthetase (CPSase), is expressed only in the presence od exogenous arginine. In unsupplemented media, synthesis of carbamylphosphate and growth was almost normal; in arginine-containing media, synthesis of carbamylphosphate stopped, as did growth, as a consequence of starvation for pyrimidine. Genetic and biochemical evidence suggests that arginine exerts this inhibition by repressing the synthesis of ornithine carbamyltransferase (OTCase), the intracellular presence of which is required for assembly of the unequal subunits and proper functioning of the mutant CPSase. After the addition of arginine to a culture of the mutant, CPSase activity (glutamine dependent) characteristic of the intact holoenzyme progressively decreased, whereas activity (ammonia dependent) characteristic of the free large (alpha) subunit increased. Extracts of mutant cells contain free small (beta) subunits, as demonstrated directly by in vitro complementation using purified alpha subunits from wild type. The mutant enzyme from cultures grown in the presence of arginine had a markedly decreased affinity for adenosine 5'-triphosphate. Mutations in argR that cause depressed synthesis of OTCase suppressed the phenotype, and a certain mutation in argI, the gene encoding OTCase, enhanced it. In vitro experiments using purified enzyme confirm the stimulatory effect of OTCase on the activity of mutant CPSase.
 ...
PMID:Arginine-sensitive phenotype of mutations in pyrA of Salmonella typhimurium: role of ornithine carbamyltransferase in the assembly of mutant carbamylphosphate synthetase. 18 93

A study was made of the capacity of insulinoma to catalyze the splitting of hippuryl-L-arginine (HA) and the contents of proinsulin-like component in the tissues of the tumours and in the blood serum of the patients. As revealed, in the absence of HA splitting by the tumour cytoplasmic fraction in the neutral pH zone there was noted a higher proinsulin-like component both in the tumour tissue and in the blood serum. An increase amount of proinsulin-like component in the blood serum stipulates possibly a more prolonged period of starvation before the occurrence of hypoglycemia, and a less pronounced picture of hypoglycemia in such patients in comparison with the patients whose tumours were capable of splitting HA similarly to the normal islands of Langerhans.
 ...
PMID:[Mechanism of hypoglycemia in insulinoma]. 19 60

Various hormonal and non-hormonal agents were tested for their ability to induce ornithine decarboxylase (EC 4.1.1.17) in primary cultures of fetal rat liver cells that retain many of the differentiated functions of hepatocytes. The only agents to induce ornithine decarboxylase in this cell type were fetal calf serum, prostaglandin E1 and cyclic AMP derivatives. Also, the amino acid arginine would induce ornithine decarboxylase in this cell type following arginine starvation for 24 h. These observations are in contrast to the wide range of hormones, e.g. insulin, hydrocortisone, glucagon and growth hormone, than can induce ornithine decarboxylase in vivo in the adult rat liver but which are all without effect on fetal rat liver cells.
 ...
PMID:Factors regulating the induction of ornithine decarboxylase in fetal rat liver cells in culture. 21 27


1 2 3 4 5 6 7 8 9 10 Next >>