The Vwa+ virulence factor of yersiniae: the molecular basis of the attendant nutritional requirement for Ca++.

The plague V antigen is a cytoplasmic 90,000-dalton peptide, and the W antigen is a primarily extracellular 145,000-dalton lipoprotein of unknown origin. Wild-type yersiniae undergo restriction of cell division when producing these plasmid-mediated virulence antigens (Vwa+) during cultivation at 37 C in Ca++-deficient media. In Yersinia pestis both restriction and synthesis of V and W antigens are potentiated in this environment by elevated Mg++ and prevented by Ca++ or exogenous nucleoside triphosphates. Restriction occurs by mechanisms that also are involved in nutritional stepdown (shutoff of stable RNA synthesis with reduction of nucleotide pools). Attendant regulatory mechanisms remain undefined; they are independent of MS nucleotides but may involve V antigen. Restriction is similar in Vwa+ Yersinia pseudotuberculosis and Yersinia enterocolitica, which, unlike Y. pestis, produce ancillary outer membrane peptides. Synthesis of these activities is dependent on elevated temperature but may not be influenced by Ca++; their presence is associated with spontaneous autoagglutination in vitro.