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Studies of the extracytoplasmic function sigma factor PG 0162 in Porphyromonas gingivalis
Author(s) -
Dou Y.,
Aruni W.,
Muthiah A.,
Roy F.,
Wang C.,
Fletcher H.M.
Publication year - 2016
Publication title -
molecular oral microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 77
eISSN - 2041-1014
pISSN - 2041-1006
DOI - 10.1111/omi.12122
Subject(s) - porphyromonas gingivalis , gene , chemistry , sigma factor , mutant , microbiology and biotechnology , escherichia coli , transcription (linguistics) , promoter , gene expression , biology , biochemistry , bacteria , genetics , linguistics , philosophy
Summary PG 0162, annotated as an extracytoplasmic function ( ECF ) sigma factor in Porphyromonas gingivalis , is composed of 193 amino acids. As previously reported, the PG 0162 ‐deficient mutant, P. gingivalis FLL 350 showed significant reduction in gingipain activity compared with the parental strain. Because this ECF sigma factor could be involved in the virulence regulation in P. gingivalis , its genetic properties were further characterized. A 5’‐ RACE analysis showed that the start of transcription of the PG 0162 gene occurred from a guanine (G) residue 69 nucleotides upstream of the ATG translation initiation codon. The function of PG 0162 as a sigma factor was confirmed in a run‐off in vitro transcription assay using the purified rPG 0162 and RNAP core enzyme from Escherichia coli with the PG 0162 promoter as template. As an appropriate PG 0162 inducing environmental signal is unknown, a strain overexpressing the PG 0162 gene designated P. gingivalis FLL 391 was created. Compared with the wild‐type strain, transcriptome analysis of P. gingivalis FLL 391 showed that approximately 24% of the genome displayed altered gene expression (260 upregulated genes; 286 downregulated genes). Two other ECF sigma factors ( PG 0985 and PG 1660) were upregulated more than two‐fold. The autoregulation of PG 0162 was confirmed with the binding of the rPG 0162 protein to the PG 0162 promoter in electrophoretic mobility shift assay. In addition, the rPG 0162 protein also showed the ability to bind to the promoter region of two genes ( PG 0521 and PG 1167 ) that were most upregulated in P. gingivalis FLL 391. Taken together, our data suggest that PG 0162 is a sigma factor that may play an important role in the virulence regulatory network in P. gingivalis .