title: Identification of disulphide stress-responsive extracytoplasmic function sigma factors in Rothia mucilaginosa.
abstract: Rothia mucilaginosa is known as a member of commensal bacterial flora in the oral cavity and has received attention as a potential opportunistic pathogen. We previously determined the genomic sequence of R. mucilaginosa DY-18, a clinical strain with biofilm-like structures isolated from an infected root canal of a tooth with persistent apical periodontitis. We found that the DY-18 genome had only two sigma factor genes that encoded the primary and extracytoplasmic function (ECF) sigma factors. Genomic analysis on the available database of R. mucilaginosa ATCC 25296 (a type strain for R. mucilaginosa) revealed that ATCC 25296 has three sigma factors: one primary sigma factor and two ECF sigma factors, one of which was highly homologous to that of DY-18. ECF sigma factors play an important role in the response to environmental stress and to the production of virulence factors. Therefore, we first examined gene-encoding sigma factors on R. mucilaginosa genome in silico. The homologous ECF sigma factors found in strains DY-18 and ATCC 25296 formed a distinct SigH (SigR) clade in a phylogenetic tree and their cognate anti-sigma factor has a HXXXCXXC motif known to respond against disulphide stress. Quantitative reverse transcription polymerase chain reaction (PCR) and microarray analysis showed that the transcriptional levels of sigH were markedly up-regulated under disulphide stress in both strains. Microarray data also demonstrated that several oxidative-stress-related genes (thioredoxin, mycothione reductase, reductase and oxidoreductase) were significantly up-regulated under the diamide stress. On the basis of these results, we conclude that the alternative sigma factor SigH of R. mucilaginosa is a candidate regulator in the redox state.
authors: Department of Bacteriology, Osaka Dental University, 8-1 Kuzuha-Hanazono, Hirakata, 573-1121 Japan. nambu-t@cc.osaka-dent.ac.jp
authors: Takayuki
authors: T
authors: Nambu
authors: Kazuyoshi
authors: K
authors: Yamane
authors: Takeshi
authors: T
authors: Yamanaka
authors: Chiho
authors: C
authors: Mashimo
authors: Hugo
authors: H
authors: Maruyama
authors: Masahiro
authors: M
authors: Yoshida
authors: Hiroyuki
authors: H
authors: Hayashi
authors: Kai-Poon
authors: KP
authors: Leung
authors: Hisanori
authors: H
authors: Fukushima
mesh_terms: D000191:Actinomycetaceae / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs / Q000235:genetics; D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics / Q000302:isolation & purification*; D003958:Diamide; D004220:Disulfides / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D005809:Genes, Regulator / Q000235:genetics; D016680:Genome, Bacterial / Q000235:genetics; D006801:Humans; D046228:Microarray Analysis; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology*; D010088:Oxidoreductases / Q000032:analysis / Q000235:genetics; D010802:Phylogeny; D012097:Repressor Proteins / Q000032:analysis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D012808:Sigma Factor / Q000032:analysis / Q000037:antagonists & inhibitors / Q000235:genetics / Q000302:isolation & purification*; D013439:Sulfhydryl Reagents; D013879:Thioredoxins / Q000032:analysis / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004220:Disulfides; D012097:Repressor Proteins; C120328:SigH protein, bacteria; D012808:Sigma Factor; D013439:Sulfhydryl Reagents; D003958:Diamide; D013879:Thioredoxins; D010088:Oxidoreductases; C121837:mycothione reductase