Characterization of the O‐antigen gene clusters of Yersinia pseudotuberculosis and the cryptic O‐antigen gene cluster of Yersinia pestis shows that the plague bacillus is most closely related to and has evolved from Y. pseudotuberculosis serotype O:1b

Abstract

One of the most virulent and feared bacterial pathogens is Yersinia pestis, the aetiologic agent of bubonic plague. Characterization of the O‐antigen gene clusters of 21 serotypes of Yersinia pseudotuberculosis and the cryptic O‐antigen gene cluster of Y. pestis showed that the plague bacillus is most closely related to and has evolved from Y. pseudotuberculosis serotype O:1b. The nucleotide sequences of both gene clusters (about 20.5 kb each) were determined and compared to identify the differences that caused the silencing of the Y. pestis gene cluster. At the nucleotide sequence level, the loci were 98.9% identical and, of the 17 biosynthetic genes identified from the O:1b gene cluster, five were inactivated in the Y. pestis cluster, four by insertions or deletions of one nucleotide and one by a deletion of 62 nucleotides. Apparently, the expression of the O‐antigen is not beneficial for the virulence or to the lifestyle of Y. pestis and, therefore, as one step in the evolution of Y. pestis, the O‐antigen gene cluster was inactivated.

Phenotypic characterization of OmpX, an Ail homologue of Yersinia pestis KIM

“…The length of O-antigen has been previously shown to regulate functions of other proteins such as Pla and PgtE (Kukkonen et al, 2004). LPS structural diversity (Skurnik et al, 2000;Zhou et al, 2004) (Yang et al, 1996). Another possible explanation of this discrepancy is the one substitution (Phe vs Val) in the predicted third (out of four) surface-exposed-loop regions of Y. pseudotuberculosis Ail.…”

Genome sequence of Yersinia pestis, the causative agent of plague

“…It might also have a role in survival in the gut by protecting the bacterium from cationic peptides, such as those produced by Paneth cells in the human small intestine 25 . Yersinia pestis produces a rough LPS, lacking an O antigen as a consequence of these mutations within the biosynthesis cluster of the O antigen 3 , but the nature of the selective advantage this may confer to Y. pestis is unexplained. The surface adhesin Ail (YPO2905) is also involved in serum resistance in Y. enterocolitica 26 .…”

“…Protective mechanisms to attenuate damage are also set in motion 2 . 2-Arachidonoyl glycerol (2-AG) is an endogenous cannabinoid, identi®ed both in the periphery 3 and in the brain 4 , but its physiological roles have been only partially clari®ed 5±7 . Here we show that, after injury to the mouse brain, 2-AG may have a neuroprotective role in which the cannabinoid system is involved.…”

Plague virulence

“…pestis is thought to have evolved from the enteropathogen Y. pseudotuberculosis [4,5]. Although almost identical genetically, the two organisms produce markedly different diseases.…”

“…An example of this phenomenon is the O antigen that is an essential virulence factor for many bacterial pathogens protecting the bacterial surface from the activity of complement. Y. pestis does not produce an O antigen as the gene cluster is inactivated by multiple mutations [5,16]. The basis for serum resistance of Y. pestis in the absence of an O antigen has not been de®ned, although it may be due in part to surface proteases such as Pla cleaving complement components [12].…”