THE CLPP PROTEIN, A SUBUNIT OF THE CLP PROTEASE, MODULATES AIL GENE-EXPRESSION IN YERSINIA-ENTEROCOLITICA

Yersinia enterocolitica is a gastrointestinal pathogen of humans and a nimals. Ail is a 17 kDa cell-surface protein that confers on Y. entero colitica resistance to serum killing and the ability to attach to and invade cells in vitro. The ail gene of Y. enterocolitica is regulated by temperature and growth phase. In stationary phase, ail transcript i s only detected when bacteria are grown at the host temperature of 37 degrees C. Our laboratory previously described a group of mini-Tn10 mu tants, which expressed ail in stationary phase at 28 degrees C. In one of these mutants, DP5102::mini-Tn10 3-2, the mini-Tn10 inserted into a gene encoding a protein with 90.3% identity to the ClpP protease sub unit from Escherichia coil. Expression of ail in stationary phase at 2 8 degrees C was also derepressed in a directed Y. enterocolitica clpP mutant. Analysis of ail transcripts in the wild-type and clpP mutant s trains indicated that there is a single start site of transcription of ail and that the effect of the clpP mutation was on the initiation of transcription at this site. Similar to E. coli, a clpX homologue was identified downstream of clpP. The Y. enterocolitica clpP gene complem ented the clpP mutant phenotype, repressing the expression of both ail transcript levels and cell surface-expressed Ail protein. Thus, ClpP has a role in the modulation of ail transcription in Y. enterocolitica .