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)

At least 78%, and perhaps all, of inorganic polyphosphate is shown to be contained within the vesicles (vacuoles) of Neurospora crassa, where over 97% of the soluble arginine, lysine, and ornithine pools are known to accumulate. Furthermore, synthetic polyphosphate can concentrate arginine up to 400-fold from dilute (0.01 mM) solutions in equilibrium dialysis. For these reasons and because the molar ratio of basic amino acids and polyphosphate phosphorus is approximately 1, we tested the hypothesis that there was an obligate physiological relationship between them. Experiments in which nitrogen starvation and arginine excess were imposed upon cells showed that polyphosphate content was insensitive to changes in the basic amino acid content. Experiments involving phosphate starvation and restoration showed that basic amino acid content was almost wholly independent of polyphosphate pools. Moreover, the normal high degree of compartmentation of arginine in vesicles was maintained despite polyphosphate depletion, and arginine was still exchanged across the vesicular membrane. We conclude that N. crassa, like yeasts, can regulate polyphosphates and basic amino acids independently, and that the accumulation of basic amino acids in vesicles may depend upon an energy-requiring mechanism in addition to the demonstrated charge interaction with polyphosphate.
 ...
PMID:Basic amino acids and inorganic polyphosphates in Neurospora crassa: independent regulation of vacuolar pools. 644 98

The general control of amino acid biosynthesis was investigated in Candida spec. EH 15/D, using single and double mutant auxotrophic strains and prototrophic revertants starved for their required amino acids. These experiments show that starvation for lysine, histidine, arginine, leucine, threonine, proline, serine, methionine, homoserine, asparagine, glutamic acid or aspartic acid can result in derepression of enzymes. A correlation was found between the degree of derepression, growth of strains, and concentration of required amino acids. The amino acids pool pattern of mutants and revertants is different from that in the wild type strain.
 ...
PMID:[General control of amino acid biosynthesis in mutants of Candida spec. EH 15/D]. 663 44

Chinese hamster ovary (CHO) cells were subjected to severe amino acid starvation for histidine, leucine, methionine, asparagine, tyrosine, glutamine, valine, and lysine, using amino acid analogs or mutations in specific aminoacyl-tRNA synthetases. At protein synthetic rates of less than 5%, in all cases, the newly synthesized proteins were found on two-dimensional electrophoretic gels to consist of a few intensely labeled spots, with the exception of lysine. This pattern could also be produced by strong inhibition of cytoplasmic protein synthesis with cycloheximide, and was abolished by preincubation with the mitochondrial protein synthesis inhibitor chloramphenicol. It appears therefore that the spots represent mitochondrial protein synthesis and that animal cells must have separate aminoacyl-tRNA synthetases for mitochondrial tRNAs corresponding to all these amino acids except, possibly, for lysine.
 ...
PMID:Selective synthesis of mitochondrial proteins by Chinese hamster ovary cells severely starved for various amino acids. 671 12

Development of multicellular fruiting bodies of Myxococcus xanthus can be induced by limitation of any of a number of different classes of amino acids. Investigated were amino acids that wild-type strains of M. xanthus are unable to synthesize (isoleucine, leucine, and valine), can synthesize at a low rate (phenylalanine), or can normally synthesize at an adequate rate (tryptophan and serine). In general, gradual rather than abrupt starvation for an essential amino acid was required for the induction of fruiting. Perhaps gradual starvation in general minimizes antagonism between amino acids present in the medium, as was documented for valine starvation. The previously reported induction of fruiting by a high concentration of threonine was shown to be specifically reversed by lysine. Threonine addition may starve cells for lysine by feedback inhibition of aspartokinase activity. Starvation for carbon-energy sources or inorganic phosphate also induced fruiting. As in other bacteria, amino acid starvation of M. xanthus leads to increases in cellular guanosine polyphosphate, usually consisting of large increases in the amount of guanosine pentaphosphate with smaller increases in the level of guanosine tetraphosphate. Guanosine polyphosphate accumulation is thus shown to be correlated with nutritional conditions that induce fruiting, and therefore may serve as an intracellular signal to trigger cells to end vegetative growth and initiate fruiting body development.
 ...
PMID:Guanosine pentaphosphate and guanosine tetraphosphate accumulation and induction of Myxococcus xanthus fruiting body development. 676 42

Strains of Escherichia coli were starved for asparagine or lysine in order to increase the in vivo level of mistranslation. In a relA strain, asparagine starvation increased the error frequency in elongation factor Tu to 0.12 mistake per asparagine codon, while with lysine starvation in the same strain the error frequency per lysine codon was 0.008. The pattern of isoelectric point changes in the altered protein produced is consistent with third position misreading in the AAN codon group. This high level of mistranslation is not seen in streptomycin resistant (rpsL) strains or in most relA+ strains.
 ...
PMID:"Two out of three" codon reading leading to mistranslation in vivo. 676 67

We have studied the mechanisms by which amino acid starvation of Escherichia coli induces resistance against the lytic and bactericidal effects of penicillin. Starvation of E. coli strain W7 of the amino acids lysine or methionine resulted in the rapid development of resistance to autolytic cell wall degradation, which may be effectively triggered in growing bacteria by a number of chemical or physical treatments. The mechanism of this effect in the amino acid-starved cells involved the production of a murein relatively resistant to the hydrolytic action of crude murein hydrolase extracts prepared from normally growing E. coli. Resistance to the autolysins was not due to the covalently linked lipoprotein. Resistance to murein hydrolase developed most rapidly and most extensively in the portion of cell wall synthesized after the onset of amino acid starvation. Lysozymes digests of the autolysin-resistant murein synthesized during the first 10 min of lysine starvation yielded (in addition to the characteristic degradation products) a high-molecular-weight material that was absent from the lysozyme-digests of control cell wall preparations. It is proposed that inhibition of protein synthesis causes a rapid modification of murein structure at the cell wall growth zone in such a manner that attachment of murein hydrolase molecules is inhibited. The mechanism may involve some aspects of the relaxed control system since protection against penicillin-induced lysis developed much slower in amino acid-starved relaxed controlled (relA) cells than in isogenic stringently controlled (relA+) bacteria.
 ...
PMID:Alteration of Escherichia coli murein during amino acid starvation. 677 63

The coat protein of the bacteriophage MS2 was found to show an increased level of charge heterogeneity when synthesized in Escherichia coli starved for Asn or Lys. No such increase was found when the host was starved for Arg, His Ile or Pro. This is the pattern predicted by "two-out-of-three" codon misreading in the coat protein gene. In the case of Asn starvation, direct measurements of the relative incorporation of Lys demonstrate that the observed charge heterogeneity is the result of mistranslation. Asn starvation increased the error frequency in coat protein to over 0.3 mistake per asparagine codon. The small amount of charge heterogeneity seen in unstarved cells seems also to be the result of misreading Asn codons.
 ...
PMID:Mistranslation in cells infected with the bacteriophage MS2: direct evidence of Lys for Asn substitution. 678 Jul 57

Amino acid starvation of a variety of different types of cells has been reported to induce protein degradation and also specific mistranslation. For certain amino acid starvations, the mistranslated protein, which contains specific amino acid substitutions, can be separated and quantified by two-dimensional polyacrylamide gel electrophoresis. In this paper, I show that this specifically mistranslated protein, made during amino acid starvation, does not seem to be preferentially degraded during continued starvation or renewed growth. Specifically mistranslated ribosomal protein is also assembled into ribosomes in the same proportion that it is made. These results imply that the amino acid substitutions apparently made (lysine for asparagine or glutamine or histidine) do not lead to proteins recognized as grossly "abnormal" by the cell's proteolysis systems.
 ...
PMID:Mistranslated protein in Escherichia coli. 702 69

The quantitative significance of the conversion in vivo of L-[U-14C]leucine to ketone bodies was determined in rats starved for 3 or 48 h. In animals starved for 3 h, 4.4% of ketone-body carbon is derived from the metabolism of leucine, and in rats starved for 48 h the corresponding value is 2.3%. This conversion occurs rapidly, and the specific radioactivity of ketone bodies in blood is maximal at 2 min after the intravenous injection of labelled leucine for both periods of starvation. The flux of leucine in the blood is 1.01 and 1.04 mumol/min per 100 g body wt. respectively for animals starved for 3 and 48 h. The specific radioactivity of blood ketone bodies was compared at 2 min after the injection of labelled leucine, lysine and phenylalanine. The specific radioactivity was 4-5 fold higher with leucine than with lysine or phenylalanine.
 ...
PMID:The role of leucine in ketogenesis in starved rats. 711 36

It has been known for several years that DNA replication and histone synthesis occur concomitantly in cultured mammalian cells. Normally all five classes of histones are synthesized coordinately. However, mouse myeloma cells, synchronized by starvation for isoleucine, synthesize increased amounts of histone H1 relative to the four nucleosomal core histones. This unscheduled synthesis of histone H1 is reduced within 1 h after refeeding isoleucine, and is not a normal component of G1. The synthesis of H1 increases coordinately again with other histones during the S phase. The DNA synthesis inhibitors, cytosine arabinoside and hydroxyurea, block all histone synthesis in S-phase cells. The levels of histone H1 mRNA, relative to the other histone mRNAs, is increased in isoleucine-starved cells and decreases rapidly after refeeding isoleucine. The increased incorporation of histone H1 is at least partially due to the low isoleucine content of histone H1. Starvation of cells for lysine resulted in a decrease in H1 synthesis relative to core histones. Again the ratio was altered on refeeding the amino acid. 3T3 cells starved for serum also incorporated only H1 histones into chromatin. The ratio of different H1 proteins also changed. The synthesis of the H1(0) protein was predominant in G0 cells, and reduced in S-phase cells. These data indicate the metabolism of H1 is independent of the other histones when cell growth is arrested.
 ...
PMID:Uncoordinate synthesis of histone H1 in cells arrested in the G1 phase. 715 89


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