title: The sensor histidine kinase RgfC affects group B streptococcal virulence factor expression independent of its response regulator RgfA.
abstract: Group B streptococci (GBS; Streptococcus agalactiae) are beta-hemolytic, Gram-positive bacteria that are common asymptomatic colonizers of healthy adults. However, these opportunistic bacteria also cause invasive infections in human newborns and in certain adult populations. To adapt to the various environments encountered during its disease cycle, GBS encodes a number of two-component signaling systems. Previous studies have indicated that the TCS comprising the sensor histidine kinase RgfC and the response regulator RgfA mediate GBS binding to extracellular matrix components, such as fibrinogen. However, in certain GBS clinical isolates, a point mutation in rgfA results in premature truncation of the response regulator. The truncated RgfA protein lacks the C-terminal DNA binding domain necessary for promoter binding and gene regulation. Here, we show that deletion of rgfC in GBS strains lacking a functional RgfA increased systemic infection. Furthermore, infection with the rgfC mutant increased induction of proinflammatory signaling pathways in vivo. Phosphoproteomic analysis revealed that 19 phosphopeptides corresponding to 12 proteins were differentially phosphorylated at aspartate, cysteine, serine, threonine, or tyrosine residues in the rgfC mutant. This included aspartate phosphorylation of a tyrosine kinase, CpsD, and a transcriptional regulator. Consistent with this observation, microarray analysis of the rgfC mutant indicated that >200 genes showed altered expression compared to the isogenic wild-type strain and included transcriptional regulators, transporters, and genes previously associated with GBS pathogenesis. Our observations suggest that in the absence of RgfA, nonspecific RgfC signaling affects the expression of virulence factors and GBS pathogenesis.
authors.affiliation: Department of Pediatric Infectious Diseases, University of Washington School of Medicine and Seattle Children's Research Institute, Seattle, Washington, USA.
authors.forename: Claire
authors.initials: C
authors.lastname: Gendrin
authors.affiliation: Department of Pediatric Infectious Diseases, University of Washington School of Medicine and Seattle Children's Research Institute, Seattle, Washington, USA.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Lembo
authors.affiliation: Department of Pediatric Infectious Diseases, University of Washington School of Medicine and Seattle Children's Research Institute, Seattle, Washington, USA Department of Global Health, University of Washington, Seattle, Washington, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Whidbey
authors.affiliation: Department of Pediatric Infectious Diseases, University of Washington School of Medicine and Seattle Children's Research Institute, Seattle, Washington, USA.
authors.forename: Kellie
authors.initials: K
authors.lastname: Burnside
authors.affiliation: Department of Pediatric Infectious Diseases, University of Washington School of Medicine and Seattle Children's Research Institute, Seattle, Washington, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Berry
authors.affiliation: Department of Pediatric Infectious Diseases, University of Washington School of Medicine and Seattle Children's Research Institute, Seattle, Washington, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Ngo
authors.affiliation: Department of Biology and Center for Microbial Sciences, San Diego State University, San Diego, California, USA.
authors.forename: Anirban
authors.initials: A
authors.lastname: Banerjee
authors.affiliation: Department of Biochemistry, Purdue University, West Lafayette, Indiana, USA.
authors.forename: Liang
authors.initials: L
authors.lastname: Xue
authors.affiliation: Department of Biochemistry, Purdue University, West Lafayette, Indiana, USA.
authors.forename: Justine
authors.initials: J
authors.lastname: Arrington
authors.affiliation: Department of Biology and Center for Microbial Sciences, San Diego State University, San Diego, California, USA.
authors.forename: Kelly S
authors.initials: KS
authors.lastname: Doran
authors.affiliation: Department of Biochemistry, Purdue University, West Lafayette, Indiana, USA.
authors.forename: W Andy
authors.initials: WA
authors.lastname: Tao
authors.affiliation: Department of Pediatric Infectious Diseases, University of Washington School of Medicine and Seattle Children's Research Institute, Seattle, Washington, USA Department of Global Health, University of Washington, Seattle, Washington, USA lakshmi.rajagopal@seattlechildrens.org.
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Rajagopal
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001921:Brain / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D002460:Cell Line; D042783:Endothelial Cells / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D000071677:Histidine Kinase; D006801:Humans; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction; D013290:Streptococcal Infections / Q000382:microbiology* / Q000473:pathology; D013292:Streptococcus agalactiae / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D014158:Transcription, Genetic; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D011494:Protein Kinases; D000071677:Histidine Kinase