Document Detail

Separate regulatory systems for the repression of metE and btuB by vitamin B12 in Escherichia coli.
MedLine Citation:
PMID:  3108627     Owner:  NLM     Status:  MEDLINE    
Synthesis of the btuB-encoded outer membrane receptor for vitamin B12 and the metE-encoded homocysteine methyltransferase is repressed by growth of Escherichia coli in the presence of vitamin B12. The regulation by vitamin B12 of the production of beta-galactosidase in strains carrying btuB-lac or metE-lac operon fusions indicated that repression of both genes operates at the transcriptional level. Selection for expression of these fusions under repressive conditions allowed isolation of second-site mutations in which repressibility by vitamin B12 had been lost. Mutations in metH and metF prevented vitamin B12-dependent regulation of metE, but not that of btuB. Mutations in btuB and other genes involved in uptake of the vitamin eliminated or reduced repression. Mutations in the newly identified gene, btuR, controlled the repressibility of btuB, but had no effect on metE regulation. The btuR gene resides at 27.9 min on the genetic map in the gene order cysB-topA-btuR-trp; it acts in a trans-dominant manner and appears to encode a repressor of btuB transcription.
M D Lundrigan; L C De Veaux; B J Mann; R J Kadner
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Molecular & general genetics : MGG     Volume:  206     ISSN:  0026-8925     ISO Abbreviation:  Mol. Gen. Genet.     Publication Date:  1987 Mar 
Date Detail:
Created Date:  1987-06-29     Completed Date:  1987-06-29     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0125036     Medline TA:  Mol Gen Genet     Country:  GERMANY, WEST    
Other Details:
Languages:  eng     Pagination:  401-7     Citation Subset:  IM    
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MeSH Terms
Bacterial Outer Membrane Proteins / biosynthesis,  genetics*
Enzyme Repression
Escherichia coli / drug effects,  enzymology,  genetics*
Gene Expression Regulation / drug effects*
Genes / drug effects*
Genes, Bacterial / drug effects*
Homocysteine S-Methyltransferase
Methyltransferases / biosynthesis,  genetics*
Vitamin B 12 / pharmacology*
beta-Galactosidase / genetics
Grant Support
Reg. No./Substance:
0/Bacterial Outer Membrane Proteins; 68-19-9/Vitamin B 12; EC 2.1.1.-/Methyltransferases; EC S-Methyltransferase; EC

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