title: Leucine-responsive regulatory protein and deoxyadenosine methylase control the phase variation and expression of the sfa and daa pili operons in Escherichia coli.
abstract: The Escherichia coli operons daa and sfa encode F1845 and S pili, respectively. In this paper we show that the expression of these operons is under phase variation control at a transcriptional level. The transcription of both operons is dependent on the global regulator leucine-responsive regulatory protein (Lrp) and deoxyadenosine methylase (Dam). Lrp is required for methylation protection of two GATC sites located within conserved DNA sequences in the regulatory regions of these operons. These GATC sites are differentially methylated, establishing a methylation pattern which is characteristic of either the phase ON or phase OFF state. We also show that Lrp binds to the daa and sfa regulatory regions and that this binding is modulated by the methylation of the GATC sites. These results indicate that the phase variation of the daa and sfa operons is regulated by a mechanism involving differential binding of Lrp owing to methylation of GATC sites in the regulatory region, which is similar to the mechanism that controls phase variation of the pap operon.
authors.affiliation: Department of Pathology, University of Utah School of Medicine, Salt Lake City 84132.
authors.forename: M W
authors.initials: MW
authors.lastname: van der Woude
authors.forename: D A
authors.initials: DA
authors.lastname: Low
mesh_terms: D018830:Adhesins, Escherichia coli; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D051756:Leucine-Responsive Regulatory Protein; D008745:Methylation; D008780:Methyltransferases / Q000502:physiology*; D008969:Molecular Sequence Data; D009876:Operon; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); D014157:Transcription Factors
chemical_list: D018830:Adhesins, Escherichia coli; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C080953:DaaA protein, E coli; C080954:DaaF protein, E coli; D029968:Escherichia coli Proteins; C497278:Lrp protein, E coli; C086707:PapI protein, E coli; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C087445:sfaB protein, E coli; C087446:sfaC protein, E coli; D051756:Leucine-Responsive Regulatory Protein; C087444:sfaA protein, E coli; D036781:Fimbriae Proteins; D008780:Methyltransferases; C058693:Dam methyltransferase; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); C499294:dam protein, E coli