title: Streptococcus pneumoniae PstS production is phosphate responsive and enhanced during growth in the murine peritoneal cavity.
abstract: Differential display-PCR (DDPCR) was used to identify a Streptococcus pneumoniae gene with enhanced transcription during growth in the murine peritoneal cavity. Northern dot blot analysis and comparative densitometry confirmed a 1.8-fold increase in expression of the encoded sequence following murine peritoneal culture (MPC) versus laboratory culture or control culture (CC). Sequencing and basic local alignment search tool analysis identified the DDPCR fragment as pstS, the phosphate-binding protein of a high-affinity phosphate uptake system. PCR amplification of the complete pstS gene followed by restriction analysis and sequencing suggests a high level of conservation between strains and serotypes. Quantitative immunodot blotting using antiserum to recombinant PstS (rPstS) demonstrated an approximately twofold increase in PstS production during MPC from that during CCs, a finding consistent with the low levels of phosphate observed in the peritoneum. Moreover, immunodot blot and Northern analysis demonstrated phosphate-dependent production of PstS in six of seven strains examined. These results identify pstS expression as responsive to the MPC environment and extracellular phosphate concentrations. Presently, it remains unclear if phosphate concentrations in vivo contribute to the regulation of pstS. Finally, polyclonal antiserum to rPstS did not inhibit growth of the pneumococcus in vitro, suggesting that antibodies do not block phosphate uptake; moreover, vaccination of mice with rPstS did not protect against intraperitoneal challenge as assessed by the 50% lethal dose.
authors.affiliation: The University of Texas Medical Branch at Galveston, Department of Microbiology and Immunology, Galveston, Texas 77555-1019, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Orihuela
authors.forename: J
authors.initials: J
authors.lastname: Mills
authors.forename: C W
authors.initials: CW
authors.lastname: Robb
authors.forename: C J
authors.initials: CJ
authors.lastname: Wilson
authors.forename: D A
authors.initials: DA
authors.lastname: Watson
authors.forename: D W
authors.initials: DW
authors.lastname: Niesel
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis* / Q000627:therapeutic use; D000070:Acebutolol / Q000302:isolation & purification; D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000627:therapeutic use; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D051379:Mice; D033902:Periplasmic Binding Proteins; D010529:Peritoneal Cavity / Q000382:microbiology*; D028044:Phosphate-Binding Proteins; D010710:Phosphates / Q000378:metabolism*; D012329:RNA, Bacterial / Q000302:isolation & purification; D018805:Sepsis / Q000517:prevention & control; D013296:Streptococcus pneumoniae / Q000235:genetics* / Q000254:growth & development* / Q000472:pathogenicity; D014611:Vaccination
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D033902:Periplasmic Binding Proteins; D028044:Phosphate-Binding Proteins; D010710:Phosphates; C090133:PstS protein, E coli; D012329:RNA, Bacterial; D000070:Acebutolol