title: Involvement of extracytoplasmic function sigma factors in virulence regulation in Porphyromonas gingivalis W83.
abstract: Extracytoplasmic function (ECF) sigma factors are known to play an important role in the bacterial response to various environmental stresses and can significantly modulate their pathogenic potential. In the genome of Porphyromonas gingivalis W83, six putative ECF sigma factors were identified. To further evaluate their role in this organism, a PCR-based linear transformation method was used to inactivate five ECF sigma factor genes (PG0162, PG0214, PG0985, PG1660, and PG1827) by allelic exchange mutagenesis. All five isogenic mutants formed black-pigmented colonies on blood agar. Mutants defective in PG0985, PG1660, and PG1827 genes were more sensitive to 0.25 mM of hydrogen peroxide compared with the wild-type strain. Isogenic mutants of PG0162 and PG1660 showed a 50% decrease in gingipain activity. Reverse transcription-PCR analysis showed that there was no alteration in the expression of rgpA, rgpB, and kgp gingipain genes in these mutants. Hemolytic and hemagglutination activities were decreased by more than 50% in the PG0162 mutant compared with the wild type. Taken together, these findings suggest that ECF sigma factors can modulate important virulence factors in P. gingivalis. ECF sigma factors encoded by the PG0162 and PG1660 genes might also be involved in the post-transcriptional regulation of the gingipains.
authors.affiliation: Department of Basic Sciences, Division of Microbiology and Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, CA 92354, USA.
authors.forename: Yuetan
authors.initials: Y
authors.lastname: Dou
authors.forename: Devon
authors.initials: D
authors.lastname: Osbourne
authors.forename: Rachelle
authors.initials: R
authors.lastname: McKenzie
authors.forename: Hansel M
authors.initials: HM
authors.lastname: Fletcher
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D016866:Bacteroidaceae Infections / Q000382:microbiology*; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism; D000080867:Gingipain Cysteine Endopeptidases; D006384:Hemagglutination; D006801:Humans; D018384:Oxidative Stress; D016966:Porphyromonas gingivalis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D021381:Protein Transport; D012756:Sheep; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D000080867:Gingipain Cysteine Endopeptidases; D012808:Sigma Factor; D003546:Cysteine Endopeptidases
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