The Yersinia pestis V antigen is a regulatory protein necessary for Ca2(+)-dependent growth and maximal expression of low-Ca2+ response virulence genes.
The low-Ca2+ response is a multicomponent virulence regulon of the human-pathogenic yersiniae in which 12 known virulence genes are coordinately regulated in response to environmental cues of temperature, Ca2+, and nucleotides such as ATP. Yersinial growth also is regulated, with full growth yield being permitted at 37 degrees C only if Ca2+ or a nucleotide is present. In this study, we constructed and characterized a mutant Yersinia pestis specifically defective in the gene encoding the V antigen, one of the virulence genes of the low-Ca2+ response. An in-frame internal deletion-insertion mutation was made by removing bases 51 through 645 of lcrV and inserting 61 new bases. The altered lcrV was introduced into the low-Ca2+ response plasmid in Y. pestis by allelic exchange, and the resulting mutant was characterized for its two-dimensional protein profiles, growth, expression of an operon fusion to another low-Ca2+ response virulence operon, and virulence in mice. The mutant had lost its Ca2+ and nucleotide requirement for growth, showed diminished expression of Ca2(+)-and nucleotide-regulated virulence genes, and was avirulent in mice. The mutation could be complemented with respect to the growth property by supplying native V antigen operon sequences in trans in high copy number (on pBR322). Partial complementation of the growth defect and almost complete complementation of the virulence defect were seen with a lower-copy-number complementing replicon (a pACYC184 derivative). The data are consistent with the interpretation that V antigen is bifunctional, with a role in regulating growth and expression of low-Ca2+ response virulence genes in addition to its putative role as a secreted virulence protein.
Price
S B
SB
Department of Microbiology and Immunology, Chandler Medical Center, University of Kentucky, Lexington 40536-0084.
Cowan
C
C
Perry
R D
RD
Straley
S C
SC
D000942:Antigens, Bacterial / Q000502:physiology*; D002118:Calcium / Q000494:pharmacology*; D002455:Cell Division / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D016254:Mutagenesis, Insertional; D052899:Pore Forming Cytotoxic Proteins; D014158:Transcription, Genetic; D014774:Virulence / Q000235:genetics; D015010:Yersinia pestis / Q000472:pathogenicity*; D001616:beta-Galactosidase / Q000096:biosynthesis
D000942:Antigens, Bacterial; C043908:LcrV protein, Yersinia; D052899:Pore Forming Cytotoxic Proteins; D001616:beta-Galactosidase; D002118:Calcium