Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.1.1.10 (methionyl-tRNA synthetase)
 387 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of abnormal proteins on cell viability was studied using artificially cleaved polypeptides. Escherichia coli methionyl-tRNA synthetase (MetRS) consists of two distinct domains and its activity is essential for cell viability. The polypeptide chain was split by linker insertion and expressed as two fragments. Two pairs of polypeptides, one split within the N-terminal domain and another at the junction of the two domains retained aminoacylation activity. The in vitro activities of these split mutants were enhanced by the presence of chaperonin, GroESL. However, cells containing these split polypeptides became sensitive to conditions that induce GroESL. The results of this work suggest that an abnormally generated protein can cause cell death under stressful conditions.
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PMID:Abnormal proteins enhance stress-induced cell death. 947 97

Serine/threonine protein kinases (STPKs) are the major participants in intracellular signal transduction in eukaryotes, such as yeasts, fungi, plants, and animals. Genome sequences indicate that these kinases are also present in prokaryotes, such as cyanobacteria. However, their roles in signal transduction in prokaryotes remain poorly understood. We have attempted to identify the roles of STPKs in response to heat stress in the prokaryotic cyanobacterium Synechocystis sp. PCC 6803, which has 12 genes for STPKs. Each gene was individually inactivated to generate a gene-knockout library of STPKs. We applied in vitro Ser/Thr protein phosphorylation and phosphoproteomics and identified the methionyl-tRNA synthetase, large subunit of RuBisCO, 6-phosphogluconate dehydrogenase, translation elongation factor Tu, heat-shock protein GrpE, and small chaperonin GroES as the putative targets for Ser/Thr phosphorylation. The expressed and purified GroES was used as an external substrate to screen the protein extracts of the individual mutants for their Ser/Thr kinase activities. The mutants that lack one of the three protein kinases, SpkC, SpkF, and SpkK, were unable to phosphorylate GroES in vitro, suggesting possible interactions between them towards their substrate. Complementation of the mutated SpkC, SpkF, and SpkK leads to the restoration of the ability of cells to phosphorylate the GroES. This suggests that these three STPKs are organized in a sequential order or a cascade and they work one after another to finally phosphorylate the GroES.
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PMID:Eukaryotic-like Ser/Thr protein kinases SpkC/F/K are involved in phosphorylation of GroES in the Cyanobacterium synechocystis. 2155 Nov 75