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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Growth of Halobacterium halobium under illumination with limiting aeration induces bacteriorhodopsin formation and renders the cells capable of photophosphorylation. Cells depleted of endogenous reserves by a starvation treatment were used to investigate the means by which energy is coupled to the active transport of [14C]proline, -leucine, and -histidine. Proline was readily accumulated by irradiated cells under anaerobiosis even when the photophosphorylation was abolished by the adenosine triphosphatase inhibitor N,N'-dicyclohexylcarbodimiide (DCCD). The uptake of proline in the dark was limited except when the cells were allowed to accumulate adenosine 5'-triphosphate (ATP) by prior light exposure or by the oxidation of glycerol. DCCD inhibited this dark uptake. These findings essentially support Mitchell's chemiosmotic theory of active transport. The driving force is apparently the proton-motive force developed when protons are extruded from irradiated bacteriorhodopsin or by the dydrolysis of ATP by membrane adenosine triphosphatase. Carbonylcyanide m-chlorophenylhydrazone (CCCP), a proton permeant known to abolish membrane potential, was a strong inhibitor of proline uptake. Leucine transport was also apparently driven by proton-motive force, although its kinetic properties differed from the proline system. Histidine transport is apparently not a chemiosmotic system. Dark- or light-exposed cells show comparable initial rats of histidine uptake, and these processes were only partially inhibited by DCCD or CCCP. The histidine system apparently does not utilize ATP per se since comparable rates of uptake were exhibited by cells of differing intracellular ATP levels. Irradiated cells did effect a greater total accumulation of histidine than dark-exposed cells. These findings suggest that ATP is needed for sustained transport.
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PMID:Energy coupling in the active transport of amino acids by bacteriohodopsin-containing cells of Halobacterium holobium. 12 52

We have examined the effects of prolonged histidine deprivation on the reversion of Salmonella typhimurium histidine auxotrophs containing either hisG46, a missense mutation (CTC----CCC), or hisG428, an ochre mutation (CAA----TAA). Both of these mutants can revert to His+ via intragenic and extragenic mechanisms. Whereas the hisG46 mutant site consists of G/C base pairs, extragenic suppression of hisG46 requires mutation at an A/T site. Conversely, the hisG428 site itself contains only A/T base pairs, and extragenic suppression of hisG428 occurs principally at G/C sites. Thus, by examining the mutational spectrum of hisG46 and hisG428 revertants that occurred in the presence and in the absence of histidine, it was possible to determine the effects of histidine starvation on mutations at G/C vs. A/T sites as well as on intragenic sites vs. extragenic suppressor sites. Using DNA-colony hybridization, we determined the DNA sequences of over 1300 hisG46 and hisG428 revertants. Histidine-independent revertants that arose during growth in liquid medium that contained histidine included both intragenic and extragenic suppressor mutations. The relative frequency of such extragenic suppressors was greatly reduced among the His+ revertants that were isolated after 5-10 days of histidine starvation on agar medium. Moreover, DNA sequence analysis revealed striking differences in the distribution of particular transversions at the hisG428 locus in revertants arising after prolonged histidine starvation as compared to those arising after growth in the presence of histidine.
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PMID:Sequence analysis of mutations arising during prolonged starvation of Salmonella typhimurium. 142 30

Periplasmic permeases are composed of four proteins, one of which has an ATP-binding site that has been postulated to be involved in energy coupling. Previous data suggested that these permeases derive energy from substrate level phosphorylation (Berger, E. A. (1973) Proc. Natl. Acad. Sci. U.S.A. 70, 1514-1518); however, conflicting results later cast doubt upon this hypothesis. Here, we make use of two well characterized periplasmic permeases and of a well characterized unc mutant (ATPase-) to examine this energetics problem in depth. We have utilized the histidine and maltose periplasmic permeases in Escherichia coli as model systems. Isogenic unc strains were used in order to study separately the effect of the proton-motive force and of ATP on transport. These parameters were analyzed concomitantly with transport assays. Starvation experiments indicate that both histidine and maltose transport require ATP generation and that a normal level of delta psi is not sufficient. Uncouplers such as carbonyl cyanide-m-chlorophenylhydrazone and 2,4-dinitrophenol dissipated the delta psi without decreasing the ATP level and without significant effect on these permeases, showing that delta psi is not needed. Inhibition of ATP synthesis by arsenate eliminates transport through both permeases, confirming the need for ATP. In agreement with previous results with the glutamine permease (Plate, C. A. (1979) J. Bacteriol. 137, 221-225), valinomycin plus K+ dissipates delta psi without affecting ATP levels and inhibits histidine transport; however, maltose transport is not inhibited under these conditions. This result is discussed in terms of the artefactual side effects caused by valinomycin/K+ treatment on some periplasmic permeases. Histidine transport is also shown to be sensitive to changes in the cytoplasmic pH. It is concluded that periplasmic permeases indeed have an obligatory requirement for ATP (or a closely related molecule), whereas the proton-motive force is neither sufficient nor essential.
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PMID:Energy coupling in bacterial periplasmic transport systems. Studies in intact Escherichia coli cells. 264 55

By using the Cu2+ method (Y. Ohsumi, K. Kitamoto, and Y. Anraku, J. Bacteriol. 170:2676-2682, 1988) for differential extraction of the vacuolar and cytosolic amino acid pools from yeast cells, the amino acid compositions of the two pools extracted from Saccharomyces cerevisiae cells, grown in synthetic medium supplemented with various amino acids, were determined. Histidine and lysine in the medium expanded the vacuolar pool extremely. Glutamate also accumulated in the cells, but mainly in the cytosol. The composition of amino acids in the cytosolic pool was fairly constant, in contrast to that in the vacuolar pool. Cells grown in synthetic medium supplemented with 10 mM arginine accumulated arginine in the vacuoles at a concentration of about 430 mM. This large arginine pool was metabolically active and was effectively utilized during nitrogen starvation. Arginine efflux from the vacuoles was coupled with K+ influx, with an arginine/K+ exchange ratio of 1, as judged by the initial rate. The vacuolar arginine pool was exchangeable with lysine added to the medium and was decreased by treatment of the cells with the mating pheromone, alpha-factor.
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PMID:Dynamic aspects of vacuolar and cytosolic amino acid pools of Saccharomyces cerevisiae. 313 4

In Neurospora crassa, histidine starvation of histidine mutants resulted in derepression of histidine, tryptophan, and arginine biosynthetic enzymes. The same tripartite derepression occurred in wild-type strain 74A when it was grown in medium supplemented with 3-amino-1,2,4-triazole, an inhibitor of histidine biosynthesis. Histidine-mediated derepression of tryptophan and arginine biosynthetic enzymes was not due to a lowered intracellular concentration of tryptophan or arginine, respectively. A discussion of possible mechanisms and of similar studies in prokaryotic and eukaryotic organisms is presented.
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PMID:Cross-pathway regulation: histidine-mediated control of histidine, tryptophan, and arginine biosynthetic enzymes in Neurospora crassa. 436 40

Three methods of ATP depletion in Salmonella typhimurium were compared. ATP concentrations were lowest after arsenate treatment. Arsenate or alpha-methylglucoside-plus-azide treatment nonspecifically lowered all nucleotide triphosphate levels. Histidine starvation in a hisF mutant was relatively specific for ATP depletion and therefore has potential in distinguishing ATP-dependent processes from processes dependent on other nucleotides.
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PMID:Comparison of methods for specific depletion of ATP in Salmonella typhimurium. 825 May 74

The photoprotective function of the ketocarotenoid astaxanthin in Haematococcus was questioned. When exposed to high irradiance and/or nutritional stress, green Haematococcus cells turned red due to accumulation of an immense quantity of the red pigment astaxanthin. Our results demonstrate that: 1) The addition of diphenylamine, an inhibitor of astaxanthin biosynthesis, causes cell death under high light intensity; 2) Red cells are susceptible to high light stress to the same extent or even higher then green ones upon exposure to a very high light intensity (4000 mumol photon m(-2)s(-1)); 3) Addition of 1O2 generators (methylene blue, rose bengal) under noninductive conditions (low light of 100 mumol photon m(-2)s(-1) induced astaxanthin accumulation. This can be reversed by an exogenous 1O2 quencher (histidine); 4) Histidine can prevent the accumulation of astaxanthin induced by phosphate starvation. We suggest that: 1) Astaxanthin is the result of the photoprotection process rather than the protective; 2) 1O2 is involved indirectly in astaxanthin accumulation process.
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PMID:Does astaxanthin protect Haematococcus against light damage? 952 27

The frequency of reversion in a histidine-requiring mutant of Saccharomyces cerevisiae increases about ten-fold in stationary cells during histidine starvation. Histidine starvation enhances a similar frequency of reversion in a tryptophan-requiring mutant. Starvation, therefore, enhances mutation frequencies in a non-adaptive manner. The base analogue 6-N-hydroxylaminopurine (HAP) added prior to plating on medium with limited histidine strongly increases reversion of the histidine mutant. HAP-induced reversion increases further in stationary starving cells with the same kinetics as that which increases spontaneous reversion. Adding HAP to the stationary starving cells does not produce any effect.
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PMID:Starvation in yeast increases non-adaptive mutation. 1007 25

The hisB gene of the filamentous fungus Aspergillus nidulans encodes imidazole glycerol-phosphate dehydratase (E.C. 4.2.1.19), which catalyses the seventh enzymatic step in histidine biosynthesis. The gene was isolated and its deduced peptide sequence of 247 amino acids showed up to 54% identity with the IGPD enzymes of organisms comprising all three kingdoms. Expression of hisB cDNA in a Saccharomyces cerevisiae his3delta mutant strain functionally complemented the growth phenotype under histidine limitation. Addition of histidine did not affect hisB mRNA levels in A. nidulans wild-type cells. Histidine starvation conditions increased the hisB transcript level four-fold, suggesting regulation by a cross-pathway regulatory network. Deletion of the complete hisB open reading frame in A. nidulans strain A234 resulted in histidine auxotrophy. Additionally, hisB deletion strains were blocked from sexual fruiting body formation on medium containing low concentrations of histidine. This developmental phenotype of the hisB deletion mutant strain correlated with the induction of the cross-pathway control system.
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PMID:Regulation of the Aspergillus nidulans hisB gene by histidine starvation. 1127 May 73

mRNA abundance for a number of genes is increased by amino acid limitation. From an array screening study in HepG2 human hepatoma cells, it was established that one set of genes affected by amino acid availability is the set associated with cell-cycle control. The present study describes the increased expression of both mRNA and protein for the cyclin-dependent kinase inhibitors p21 and p27 in response to deprivation of HepG2 cells for a single essential amino acid, histidine. The increase in p21 and p27 mRNA content depended on de novo protein synthesis and involved a post-transcriptional mRNA stabilization component. For p21, increase in mRNA by histidine depletion appeared to be independent of p53 transactivation, and the absolute level of p53 protein was unaffected by this treatment. Histidine limitation caused an increase in the phosphorylation of ERK1/ERK2 (extracellular-signal-regulated kinase), and inhibition of the ERK signal transduction pathway resulted in a reduction in the starvation-dependent increase in p21 mRNA. Blockade of the phosphoinositide 3-kinase and mTOR (mammalian target of rapamycin) pathways also blunted the increase in p21 mRNA content. These results document the amino acid-dependent control of the synthesis of specific cell-cycle regulators and help to explain the block at G1 phase after amino acid limitation.
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PMID:Induction of p21 and p27 expression by amino acid deprivation of HepG2 human hepatoma cells involves mRNA stabilization. 1471 82


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