title: Regulation of the pspA virulence factor and essential pcsB murein biosynthetic genes by the phosphorylated VicR (YycF) response regulator in Streptococcus pneumoniae.
abstract: The VicRK (YycFG) two-component regulatory system (TCS) is required for virulence of the human respiratory pathogen Streptococcus pneumoniae (pneumococcus). The VicR (YycF) response regulator (RR) is essential through its positive regulation of pcsB, which encodes an extracellular protein that mediates murein biosynthesis. To determine other genes that are regulated by VicR, we performed microarray analyses on a unique DeltavicR deletion mutant, which was constructed by uncoupling regulation of pcsB. Results from these microarray experiments support the idea that the VicR RR exerts strong positive regulation on the transcription of a set of genes encoding important surface proteins, including the PspA virulence factor, two proteins (Spr0096 and Spr1875) containing LysM peptidoglycan-binding domains, and a putative membrane protein (Spr0709) of unknown function. To demonstrate direct regulation, we performed band shift and footprinting experiments using purified unphosphorylated VicR and phosphorylated VicR-P, which was prepared by reaction with acetyl phosphate. VicR and VicR-P bound to regions upstream of pcsB, pspA, spr0096, spr1875, and spr0709. Phosphorylation of VicR to VicR-P increased the apparent strength and changed the nature of binding to these regions. DNase I footprinting of VicR and VicR-P bound to regions upstream of pcsB, pspA, spr0096, and spr1875 showed protection of extended regions containing a degenerate sequence related to a previously proposed consensus. These combined approaches did not support autoregulation of the vicRKX operon or substantive direct regulation of fatty acid biosynthesis by VicR or VicR-P. However, the DeltavicR mutant required fatty acids in some conditions, which supports the notion that the VicRK TCS may mediate membrane integrity as well as murein biosynthesis and virulence factor expression in S. pneumoniae.
authors.affiliation: Department of Biology, Indiana University, Jordan Hall 142, Bloomington, IN 47405, USA.
authors.forename: Wai-Leung
authors.initials: WL
authors.lastname: Ng
authors.forename: Ho-Ching Tiffany
authors.initials: HC
authors.lastname: Tsui
authors.forename: Malcolm E
authors.initials: ME
authors.lastname: Winkler
mesh_terms: D024506:5' Flanking Region; D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000032:analysis; D024202:Electrophoretic Mobility Shift Assay; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D010457:Peptidoglycan / Q000096:biosynthesis*; D010766:Phosphorylation; D011485:Protein Binding; D012329:RNA, Bacterial / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D015398:Signal Transduction; D013296:Streptococcus pneumoniae / Q000235:genetics* / Q000502:physiology; D037521:Virulence Factors / Q000096:biosynthesis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D010457:Peptidoglycan; D012329:RNA, Bacterial; D012333:RNA, Messenger; D037521:Virulence Factors; C119939:YycF protein, Bacteria; C051592:pneumococcal surface protein A