title: Role of sigma54 in the regulation of genes involved in type I and type IV pili biogenesis in Xylella fastidiosa.
abstract: The phytopathogen Xylella fastidiosa produces long type IV pili and short type I pili involved in motility and adhesion. In this work, we have investigated the role of sigma factor sigma(54) (RpoN) in the regulation of fimbrial biogenesis in X. fastidiosa. An rpoN null mutant was constructed from the non-pathogenic citrus strain J1a12, and microarray analyses of global gene expression comparing the wild type and rpoN mutant strains showed few genes exhibiting differential expression. In particular, gene pilA1 (XF2542), which encodes the structural pilin protein of type IV pili, showed decreased expression in the rpoN mutant, whereas two-fold higher expression of an operon encoding proteins of type I pili was detected, as confirmed by quantitative RT-PCR (qRT-PCR) analysis. The transcriptional start site of pilA1 was determined by primer extension, downstream of a sigma(54)-dependent promoter. Microarray and qRT-PCR data demonstrated that expression of only one of the five pilA paralogues, pilA1, was significantly reduced in the rpoN mutant. The rpoN mutant made more biofilm than the wild type strain and presented a cell-cell aggregative phenotype. These results indicate that sigma(54) differentially regulates genes involved in type IV and type I fimbrial biogenesis, and is involved in biofilm formation in X. fastidiosa.
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes 1374, 05508-000 São Paulo, SP, Brazil.
authors.forename: José F
authors.initials: JF
authors.lastname: da Silva Neto
authors.forename: Tie
authors.initials: T
authors.lastname: Koide
authors.forename: Cecília M
authors.initials: CM
authors.lastname: Abe
authors.forename: Suely L
authors.initials: SL
authors.lastname: Gomes
authors.forename: Marilis V
authors.initials: MV
authors.lastname: Marques
mesh_terms: D000595:Amino Acid Sequence; D001422:Bacterial Adhesion / Q000235:genetics; D001483:Base Sequence; D018441:Biofilms / Q000254:growth & development; D002957:Citrus; D036781:Fimbriae Proteins / Q000235:genetics; D010861:Fimbriae, Bacterial / Q000235:genetics* / Q000648:ultrastructure; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D051877:RNA Polymerase Sigma 54 / Q000235:genetics* / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D024363:Transcription Initiation Site; D044167:Xylella / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D036781:Fimbriae Proteins; D051877:RNA Polymerase Sigma 54