title: The Escherichia coli modE gene: effect of modE mutations on molybdate dependent modA expression.
abstract: The Escherichia coli modABCD operon, which encodes a high-affinity molybdate uptake system, is transcriptionally regulated in response to molybdate availability by ModE. Here we describe a highly effective enrichment protocol, applicable to any gene with a repressor role, and establish its application in the isolation of transposon mutations in modE. In addition we show that disruption of the ModE C-terminus abolishes derepression in the absence of molybdate, implying this region of ModE controls the repressor activity. Finally, a mutational analysis of a proposed molybdate binding motif indicates that this motif does not function in regulating the repressor activity of ModE.
authors.affiliation: Department of Microbiology and Molecular Genetics, University of California at Los Angeles 90095-1489, USA.
authors.forename: P M
authors.initials: PM
authors.lastname: McNicholas
authors.forename: R C
authors.initials: RC
authors.lastname: Chiang
authors.forename: R P
authors.initials: RP
authors.lastname: Gunsalus
mesh_terms: D001426:Bacterial Proteins; D004252:DNA Mutational Analysis; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000502:physiology; D005798:Genes, Bacterial / Q000502:physiology; D005809:Genes, Regulator / Q000502:physiology; D008291:Malate Dehydrogenase / Q000235:genetics*; D008969:Molecular Sequence Data; D008982:Molybdenum / Q000378:metabolism / Q000494:pharmacology*; D009154:Mutation / Q000502:physiology; D009876:Operon / Q000502:physiology; D010957:Plasmids; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C491064:ModE protein, E coli; C101050:ModE protein, bacteria; D014157:Transcription Factors; C044659:molybdate; D008982:Molybdenum; D008291:Malate Dehydrogenase; C031917:malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+)