Nucleotide sequence and transcription analysis of yop51 from Yersinia enterocolitica W22703.

Virulent strains of Yersinia enterocolitica, pseudotuberculosis and pestis secrete large amounts of plasmid-encoded proteins involved in virulence and called Yops. A 2 kb fragment of the pYVe227 plasmid from Yersinia enterocolitica 0:9 encoding Yop51 was sequenced. Gene yop51 was found to encode a 50,882 Da protein consisting of 468 amino acids. This protein shows 99% identity with Yop2b, its counterpart from Y. pseudotuberculosis YPIII (pIB1), confirming that the virulence machinery is highly conserved among Yersinia spp. The homology stops abruptly 240 bp upstream and 175 bp downstream of the structural yop51 gene suggesting that all the sequences involved in the regulation of yop51 are located within the conserved region and confirming that the homology between the plasmids of Yersinia enterocolitica and Yersinia pseudotuberculosis is made up of boxes of high homology. Gene yop51 is only transcribed at 37 degrees C from a VirF-regulated promoter. This promoter was tentatively identified by determining the messenger transcriptional startpoint. The putative yop51 promoter resembles E. coli promoters despite the fact that it is not active in that species in the absence of VirF. A transcription terminator was found at the end of the gene while a second terminator was detected within the structural gene leading to premature termination of some of the messenger molecules.