Major stable peptides of Yersinia pestis synthesized during the low-calcium response.
It is established that the medically significant yersiniae require the presence of physiological levels of Ca2+ (ca. 2.5 mM) for sustained growth at 37 degrees C and that this nutritional requirement is mediated by a shared ca. 70-kb Lcr plasmid. The latter also encodes virulence factors (Yersinia outer membrane proteins [Yops] and V antigen) known to be selectively synthesized in vitro at 37 degrees C in Ca(2+)-deficient medium. In this study, cells of Yersinia pestis KIM were first starved for Ca2+ at 37 degrees C to prevent synthesis of bulk vegetative protein and then, after cell division had ceased, pulsed with [35S]methionine. After sufficient chase to ensure plasminogen activator-mediated degradation of Yops, the remaining major radioactive peptides were separated by conventional chromatographic methods and identified as Lcr plasmid-encoded V antigen and LcrH (and possibly LcrG), ca. 10-kb Pst plasmid-encoded pesticin and plasminogen activator, ca. 100-kb Tox plasmid-encoded fraction 1 (capsular) antigen and murine exotoxin, and chromosomally encoded antigen 4 (pH 6 antigen) and antigen 5 (a novel hemin-rich peptide possessing modest catalase activity but not superoxide dismutase activity). Also produced at high concentration was a chromosome-encoded GroEL-like chaperone protein. Accordingly, the transcriptional block preventing synthesis of bulk vegetative protein at 37 degrees C in Ca(2+)-deficient medium may not apply to genes encoding virulence factors or to highly conserved GroEL (known in other species to utilize a secondary stress-induced sigma factor).
Mehigh
R J
RJ
Department of Microbiology, Michigan State University, East Lansing 48824-1101.
Braubaker
R R
RR
D001345:Autoradiography; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000276:immunology / Q000302:isolation & purification; D002118:Calcium / Q000494:pharmacology*; D002845:Chromatography; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D008970:Molecular Weight; D014774:Virulence / Q000187:drug effects; D015010:Yersinia pestis / Q000187:drug effects / Q000378:metabolism* / Q000472:pathogenicity
D001426:Bacterial Proteins; D002118:Calcium