title: Transcriptional regulation of type 4 pilin genes and the site-specific recombinase gene, piv, in Moraxella lacunata and Moraxella bovis.
abstract: Moraxella lacunata and Moraxella bovis use type 4 pili to adhere to epithelial tissues of the cornea and conjunctiva. Primer extension analyses were used to map the transcriptional start sites for the genes encoding the major pilin subunits (tfpQ/I) and the DNA invertase (piv), which determines pilin type expression. tfpQ/I transcription starts at a sigma54-dependent promoter (tfpQ/Ip2) and, under certain growth conditions, this transcription is accompanied by weaker upstream transcription that starts at a potential sigma70-dependent promoter (tfpQ/Ip1). piv is expressed in both M. lacunata and M. bovis from a putative sigma70-dependent promoter (pivp) under all conditions assayed. Sigma54-dependent promoters require activators in order to initiate transcription; therefore, it is likely that tfpQ/Ip2 is also regulated by an activator in Moraxella. Primer extension assays with RNA isolated from Escherichia coli containing the subcloned pilin inversion region from M. lacunata showed that pivp is used for the expression of piv; however, tfpQ/Ip2 is not used for the transcription of tfpQ/I. Transcription from tfpQ/Ip2 was activated in E. coli when the sensor (PilS) and response regulator (PilR) proteins of type 4 pilin transcription in Pseudomonas aeruginosa were expressed from a plasmid. These results suggest that the expression of the type 4 pilin in M. lacunata and M. bovis is regulated not only by a site-specific DNA inversion system but also by a regulatory system which is functionally analogous to the PilS-PilR two-component system of P. aeruginosa.
authors.affiliation: Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Heinrich
authors.forename: A C
authors.initials: AC
authors.lastname: Glasgow
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D004254:DNA Nucleotidyltransferases / Q000235:genetics*; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D036781:Fimbriae Proteins; D015964:Gene Expression Regulation, Bacterial; D019426:Integrases; D008969:Molecular Sequence Data; D009016:Moraxella / Q000235:genetics* / Q000254:growth & development; D016955:Moraxella bovis / Q000235:genetics / Q000254:growth & development; D011401:Promoter Regions, Genetic; D011550:Pseudomonas aeruginosa / Q000235:genetics; D051877:RNA Polymerase Sigma 54; D045522:Recombinases; D012808:Sigma Factor / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D045522:Recombinases; D012808:Sigma Factor; D014157:Transcription Factors; C080687:pilS protein, Bacteria; C497751:rpoN protein, E coli; C074774:pilR protein, Pseudomonas aeruginosa; D036781:Fimbriae Proteins; D004254:DNA Nucleotidyltransferases; D019426:Integrases; C115006:integron integrase IntI1; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54