title: Repression of Rgg But Not Upregulation of LacD.1 inemm1-typecovSMutant Mediates the SpeB Repression in Group AStreptococcus.
abstract: CovR/CovS is an important two-component regulatory system in human pathogen group AStreptococcus(GAS). Epidemiological studies have shown that inactivation of the sensor kinase CovS is correlated with invasive clinical manifestations. The phosphorylation level of response regulator CovR decreases dramatically in the absence of CovS, resulting in the derepression of virulence factor expression and an increase in bacterial invasiveness. Streptococcal pyrogenic exotoxin B (SpeB) is a cysteine protease and is negatively regulated by CovR; however, the expression of SpeB is almost completely repressed in thecovSmutant. The present study found that in theemm1-type A20 strain, non-phosphorylated CovR acts as a transcriptional repressor for SpeB-positive regulator Rgg. In addition, the expression of Rgg-negative regulator LacD.1 is upregulated in thecovSmutant. These results suggest that inactivation of Rgg in thecovSmutant would directly mediatespeBrepression. The current study showed that overexpression ofrggbut not inactivation oflacD.1in thecovSmutant partially restoresspeBexpression, indicating that onlyrggrepression, but notlacD.1upregulation, contributes to thespeBrepression in thecovSmutant.
authors.affiliation: Department of Microbiology and Immunology, College of Medicine, Chang Gung UniversityTao-yuan, Taiwan; Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung UniversityTao-Yuan, Taiwan; Molecular Infectious Disease Research Center, Chang Gung Memorial HospitalTao-yuan, Taiwan.
authors.forename: Chuan
authors.initials: C
authors.lastname: Chiang-Ni
authors.affiliation: Department of Microbiology and Immunology, College of Medicine, Chang Gung University Tao-yuan, Taiwan.
authors.forename: Teng-Ping
authors.initials: TP
authors.lastname: Chu
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung UniversityTainan, Taiwan; Department of Biotechnology and Laboratory Science in Medicine, School of Biomedical Science and Engineering, National Yang-Ming UniversityTaipei, Taiwan.
authors.forename: Jiunn-Jong
authors.initials: JJ
authors.lastname: Wu
authors.affiliation: Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung UniversityTao-Yuan, Taiwan; Molecular Infectious Disease Research Center, Chang Gung Memorial HospitalTao-yuan, Taiwan; Department of Pediatrics, Chang Gung Children's HospitalTao-yuan, Taiwan.
authors.forename: Cheng-Hsun
authors.initials: CH
authors.lastname: Chiu
keywords: CovR/CovS; LacD.1; Rgg; SpeB; group A Streptococcus