Regulation of methionine synthesis in Escherichia coli.
The biosynthesis of methionine in Escherichia coli is under complex regulation. The repression of the biosynthetic pathway by methionine is mediated by a repressor protein (MetJ protein) and S-adenosyl-methionine which functions as a corepressor for the MetJ protein. Recently, a new regulatory locus, metR, has been identified. The MetR protein is required for both metE and metH gene expression, and functions as a transactivator of transcription of these genes. MetR is a unique prokaryotic transcription activator in that it possesses a leucine zipper motif, first described for eukaryotic DNA-binding proteins. The transcriptional activity of MetR is modulated by homocysteine, the metabolic precursor of methionine. Finally, it is known that vitamin B12 can repress expression of the metE gene. This effect is mediated by the MetH holoenzyme, which contains a cobamide prosthetic group.
Weissbach
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Roche Research Center, Roche Institute of Molecular Biology, Nutley, New Jersey 07110.
Brot
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D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006711:Homocystine / Q000378:metabolism; D016350:Leucine Zippers; D008715:Methionine / Q000096:biosynthesis / Q000235:genetics*; D008780:Methyltransferases; D008969:Molecular Sequence Data; D015534:Trans-Activators / Q000235:genetics; D014805:Vitamin B 12 / Q000378:metabolism
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C058169:MetR protein, Bacteria; D015534:Trans-Activators; D006711:Homocystine; D008715:Methionine; D008780:Methyltransferases; D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; C058170:metE protein, E coli; D014805:Vitamin B 12