FIGURE 10.

Influence of YmoA on the CsrABC-RovM-RovA-InvA cascade in Y. pseudotuberculosis. YmoA is a global virulence regulator of Y. pseudotuberculosis which is expressed under environmental conditions reflecting the initial stages of infection. It activates the synthesis of early-phase cell internalization factor invasin (InvA) which is important for colonization. This seems to occur together with H-NS, which is known to form heteromeric complexes with YmoA, through regulation of the degradation of the regulatory RNA CsrC at the first stem-loop structure of the CsrC RNA. Influence of YmoA on CsrC occurs independently of Hfq, which was also involved in Csr system control. YmoA and H-NS influence on CsrC is indirect and most likely occurs through RNA-processing factors. As a consequence of YmoA-mediated CsrC upregulation the CsrA-RovM-RovA regulator cascade is activated, leading to expression of colonization factors such as invasin. Dark arrows display direct activation, T represents repression, and dashed arrows indicate (indirect) activation by an unknown molecular mechanism.