VIRULENCE OF YERSINIA-ENTEROCOLITICA IS CLOSELY ASSOCIATED WITH SIDEROPHORE PRODUCTION, EXPRESSION OF AN IRON-REPRESSIBLE OUTER-MEMBRANE POLYPEPTIDE OF 65000 DA AND PESTICIN SENSITIVITY

Iron-repressible outer membrane proteins (Irp) and siderophore product ion of Yersinia enterocolitica, serotype 08, were subjected to analysi s. Here four Irps of apparent molecular weights of 62 000, 65 000, 740 00 and 75000 could be identified which were expressed constitutively b y a fur mutant. Production of a novel catechol-containing siderophore (denoted yersiniabactin) was detected by siderophore-indicator agar (c hrome azurol S) and feeding experiments. Growth support by yersiniabac tin under iron-restricted conditions was TonB- and Irp65-dependent and correlated with pesticin-sensitivity of Yersinia enterocolitica and E scherichia coli phi. From these results we conclude that Irp65 of Y. e nterocolitica functions as yersiniabactin receptor (FyuA) and as pesti cin receptor. By immunoblotting using rabbit antibodies against Irp65 and chrome azurol S-agar, we were able to demonstrate that all tested mouselethal Y. enterocolitica and Yersinia pseudotuberculosis strains of different serotypes express siderophores and Irp65. Moreover, the a nti-Irp65 rabbit serum did not cross-react with the known iron-repress ible high-molecular-weight proteins (HMWPs). Evidently, the mouse leth ality trait in enteropathogenic Yersinia spp. is closely associated wi th a novel iron-uptake system, comprising the production of a sideroph ore and a siderophore receptor of apparent molecular mass 65 000 Da.