THE YERSINIA YOP VIRULON - LCRV IS REQUIRED FOR EXTRUSION OF THE TRANSLOCATORS YOPB AND YOPD

LcrV, an essential piece of the Yop virulon, is encoded by the large l crGVsycDyopBD operon. In spite of repeated efforts, the role of LcrV i n the Yop virulon remains elusive. In an attempt to clarify this, we e ngineered a complete deletion of lcrV in the pYV plasmid of Yersinia e nterocolitica E40 and characterized the phenotype of the mutant. Compl ementation experiments showed that the mutation was not polar with reg ard to yopB and yopD. Nevertheless the mutation abolished secretion of YopB and YopD, while secretion of the other Yops was unaffected or ev en increased. Northern blot analysis showed that transcription of yopD was not affected. YopD could be detected inside the bacteria, shelvin g that the lack of its secretion was not due to a lack of translation or to proteolysis, This indicated that LcrV is specifically involved i n the process of release of YopB and YopD. We then investigated the po ssible interactions between LcrV and YopB or YopD. We constructed a gl utathione S-transferase-LcrV hybrid protein, and we observed that eith er YopB or YopD could be copurified with it. The same approach showed that LcrV also interacts with LcrG but not with the chaperone SycD, Us ing deletants of lcrV, we then identified a definite LcrG-binding doma in in the C terminus of LcrV.