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

Pyrrolidone carboxyl peptidase (Pcp) is an aminopeptidase (EC 3.4.11.8) able to specifically remove the L-pyroglutamyl residue from the amino-terminus of polypeptides. Since nothing was known concerning the regulation and function of Pcps, a mutant of a milk-isolated strain lacking Pcp activity (Pseudomonas fluorescens MB1), was constructed by homologous recombination using a transcriptional fusion between pcp and a reporter gene (uidA). The wild-type and mutant strains were grown in synthetic media and in milk to investigate the environmental effects on pcp transcription. The expression of pcp and of the transcriptional fusion pcp::uidA was not sensitive to environmental conditions like temperature, osmolarity or nitrogen and phosphate starvation but was induced by the product of the enzymatic activity, pyroglutamic acid (pGlu). The expression of the native gene and the fusion in inducing conditions was also controlled by the iron concentration. The identification in the pcp promoter sequence of putative ferric uptake regulator (Fur) binding sites suggests a transcriptional regulation in a Fur-dependent fashion. Two other putative regulatory stretches, corresponding to inverted repeated sequences with perfect and imperfect symmetry, were also identified. pGlu and iron are therefore at least two of the transcriptional effectors of pcp expression.
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PMID:Pyroglutamic acid and iron regulate the expression of the pcp gene in Pseudomonas fluorescens MFO. 935 Dec 3

During iron starvation the Gram-negative pathogenic bacterium Pseudomonas aeruginosa makes the nonribosomal peptide siderophore pyochelin by a four protein, 11 domain assembly line, involving a cascade of acyl-S-enzyme intermediates on the PchE and PchF subunits that are elongated, heterocyclized, reduced, and N-methylated before release. Purified PchG is shown to be an NADPH-dependent reductase for the hydroxyphenylbisthiazoline-S-PchF acyl enzyme, regiospecifically converting one of the dihydroheterocyclic thiazoline rings to a thiazolidine. The K(m) for the PchG protein is 1 microM, and the k(cat) for throughput to pyochelin is 2 min(-1). The nitrogen of the newly generated thiazolidine ring can be N-methylated upon addition of SAM, to yield the mature pyochelin chain still tethered as a pyochelinyl-S-PchF at the PCP domain. A presumed methyltransferase (MT) domain embedded in the PchF subunit catalyzes this N-methylation. Mutation of a conserved G to R in the MT core motif abolishes MT activity and subsequent chain release from PchF. The thioesterase (TE) domain of PchF catalyzes hydrolytic release of the fully mature pyochelinyl chain to produce the pyochelin siderophore at a rate of 2 min(-1), at least 30-40-fold faster than in the absence of hydroxyphenylbisthiazolinyl-COOH (HPTT-COOH) chain reduction and N-methylation. A mutation in the PchF TE domain does not catalyze autodeacylation and release of the pyochelinyl-S-enzyme. Thus, full reconstitution of the nonribosomal peptide synthetase assembly line by purified protein components has been obtained for production of this tandem bisheterocyclic siderophore.
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PMID:In vitro reconstitution of the Pseudomonas aeruginosa nonribosomal peptide synthesis of pyochelin: characterization of backbone tailoring thiazoline reductase and N-methyltransferase activities. 1146 65

The binding of sequence-specific RNA-interacting proteins, such as the bacteriophage MS2 or PP7 coat proteins, to their corresponding target sequences has been extremely useful and widely used to visualize single mRNAs in vivo. However, introduction of MS2 stem-loops into yeast mRNAs has recently been shown to lead to the accumulation of RNA fragments, suggesting that the loops impair mRNA decay. This result was questioned, because fragment occurrence was mainly assessed using ensemble methods, and their cellular localization and its implications had not been addressed on a single transcript level. Here, we demonstrate that the introduction of either MS2 stem-loops (MS2SL) or PP7 stem-loops (PP7SL) can affect the processing and subcellular localization of mRNA. We use single-molecule fluorescence in situ hybridization (smFISH) to determine the localization of three independent mRNAs tagged with the stem-loop labeling systems in glucose-rich and glucose starvation conditions. Transcripts containing MS2SL or PP7SL display aberrant localization in both the nucleus and the cytoplasm. These defects are most prominent in glucose starvation conditions, with nuclear mRNA processing being altered and stem-loop fragments abnormally enriching in processing bodies (PBs). The mislocalization of SL-containing RNAs is independent of the presence of the MS2 or PP7 coat protein (MCP or PCP).
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PMID:Stem-loop RNA labeling can affect nuclear and cytoplasmic mRNA processing. 2809 43