DNA-SEQUENCING OF THE GENE ENCODING A BACTERIAL SUPERANTIGEN, YERSINIA PSEUDOTUBERCULOSIS-DERIVED MITOGEN (YPM), AND CHARACTERIZATION OF THE GENE-PRODUCT, CLONED YPM

Previously, we found a novel bacterial superantigen from Yersinia pseu dotuberculosis, designated Y. pseudotuberculosis-derived mitogen (YPM) . In the present study, we analyzed the DNA sequence of the gene encod ing YPM. The YPM gene was cloned into a plasmid vector pMW119 and expr essed in Escherichia coli DH10B. Like the native YPM, the cloned YPM r equired the expression of MHC class II molecules on accessory cells in the induction of IL-2 production by human T cells. TCR-V beta reperto ire of human T cells reactive with the cloned YPM was V beta 3, V beta 9, V beta 13.1, and V beta 13.2. This repertoire is the same as that of T cells reactive with the native YPM. These results indicate that t he cloned YPM expressed in E. coli is identical to the native YPM. Seq uencing of the YPM gene revealed that the gene contained an open readi ng frame of 456 base pairs encoding a precursor form of 151 amino acid residues with m.w. 16,679 that is processed into a mature form of 131 amino acid residues with m.w. 14,529. Homology analysis revealed that the homology of amino acid sequence is quite low among YPM and other well known bacterial superantigens. We designated the gene encoding YP M as ypm.