Expression of iron-regulated proteins in Yersinia species and their relation to virulence.

Under iron-starvation conditions, the different Yersinia species expressed various iron-regulated proteins. Among them, two high-molecular-weight outer membrane proteins were synthesized in high-virulence-phenotype Y. pestis, Y. pseudotuberculosis, and Y. enterocolitica serovars O:8 and O:Tacoma but were present neither in low-virulence phenotype Y. enterocolitica serovars O:3 and O:9 nor in avirulent Y. frederiksenii, Y. kristensenii, Y. intermedia, and Y. enterocolitica serovar O:39. Thus, the degree of virulence correlates with the presence of the two high-molecular-weight proteins in Yersinia species.