Evidence for the presence in Burkholderia pseudomallei of a type III secretion system-associated gene cluster

Burkholderia pseudomallei, the causative agent of melioidosis, contains a c luster of putative genes homologous to those encoding HpaP, HrcQ, HrcR, Hrc S and HrpV in the plant pathogen Ralstonia solanacearum. In R. solanacearum , these genes form part of a type III secretion-associated pathogenicity is land. The order of the genes in B. pseudomallei is directly equivalent to t hat found in R, solanacearum. The B. pseudomallei proteins share 49.5% (Hpa P), 52.6% (HrcQ), 80.0% (HrcR), 72.1% (HrcS) and 46.7% (HrpV) similarity, r espectively, with their equivalent R, solanacearum proteins. The presence o f type III secretion-associated genes in B. pseudomallei pathogens suggests a possible role for type III secretion systems in the pathogenicity of thi s organism.