EXPRESSION OF INVASIN AND MOTILITY ARE COORDINATELY REGULATED IN YERSINIA-ENTEROCOLITICA

The Yersinia enterocolitica inv gene encodes the primary invasion fact or invasin, which has been previously shown to be critical in the init ial stages of infection. The expression of inv is influenced by growth phase and temperature and is maximal during late exponential-early st ationary phase at 23 degrees C. In addition, motility of Y. enterocoli tica is regulated by temperature. Y. enterocolitica cells are motile w hen grown at lower temperatures (30 degrees C or below), while bacteri a grown at 37 degrees C are nonmotile. This study was initiated to det ermine the molecular basis for the temperature regulation of inv expre ssion. Two mutants were isolated that both showed a significant decrea se in invasin expression but are hypermotile when grown at 23 degrees C. The first mutant (JB1A8v) was a result of a random mTn5Km insertion into the uvrC gene. The uvrC mutant JB1A8v demonstrated a significant decrease in inv and an increase in fleB (encodes flagellin) expressio n. These results suggest that expression of inv and flagellin genes is coordinated at the level of transcription. The second regulatory muta nt, JB16v, was a result of a targeted insertion into a locus similar t o sspA which in E. coli encodes a Stationary-phase regulator. The E. c oli sspA gene was cloned and assayed for complementation in both of th e regulatory mutants. It was determined that E. coil sspA restored inv asin expression in both the uvrC mutant and the sspA mutant. In additi on, the complementing clone decreased flagellin levels in these mutant s.