title: Control of gonococcal pilin-encoding gene expression in Escherichia coli.
abstract: The pilE gene from Neisseria gonorrhoeae, unlike other type-4 pilin-encoding genes, is well expressed in Escherichia coli. Two putative promoters have been implicated in the transcription of this gene. Besides the -24/-12 promoter used to transcribe type-4 pilin-encoding genes in most species, the consensus sequence for a conventional promoter is also present. The two promoters overlap and would have almost identical transcription start points (tsp). Transcription from a -24/-12 promoter should be abolished in an E. coli rpoN mutant. A recombinant plasmid carrying pilE could not be transformed into such a mutant, apparently because the synthesis of the N-terminal hydrophobic domain of pilin is lethal to the rpoN mutant. This suggests that pilE is expressed at a higher level in an rpoN mutant than it is in a wild-type (wt) strain of E. coli. This suggestion was confirmed by constructing fusions between the pilE promoter region and a promoter-less cat gene. We suggest that the conventional promoter is primarily responsible for the transcription of pilE, but that the binding of the RpoN sigma factor partially represses transcription of this gene in wt strains. In an rpoN mutant, the repression is removed and transcription occurs at a level that is lethal to the mutant host.
authors.affiliation: Department of Microbiology, Monash University, Clayton, Victoria, Australia.
authors.forename: J A
authors.initials: JA
authors.lastname: Fyfe
authors.forename: R A
authors.initials: RA
authors.lastname: Strugnell
authors.forename: J K
authors.initials: JK
authors.lastname: Davies
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D036781:Fimbriae Proteins; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D009344:Neisseria gonorrhoeae / Q000235:genetics*; D011401:Promoter Regions, Genetic; D051877:RNA Polymerase Sigma 54; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism; D014169:Transformation, Bacterial
chemical_list: D001425:Bacterial Outer Membrane Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D012097:Repressor Proteins; D012808:Sigma Factor; C497751:rpoN protein, E coli; D036781:Fimbriae Proteins; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54