In addition to identifying 4,012 genes, comprising 84 percent of the sequence, the work reveals an unusually dynamic genome, with genes added, moved, and silenced into pseudogenehood. "This flexibility in its genome has made Yersinia pestis a finely tuned pathogen that is adaptable to new routes of transmission to humans. This is like watching evolution in action," says Brendan Wren, professor of microbial pathogenesis at the London School of Hygiene and Tropical Medicine.
Clues in the genome support the hypothesis that Y. pestis evolved, 1,500 to 20,000 years ago, from the less fearsome human enteric pathogen Y. pseudotuberculosis. In 1999, researchers from the Max Planck Institute for Molecular Genetics and the Pasteur Institute compared six genes among 36 strains of Y. pestis and 13 of Y. pseudotuberculosis. The near genetic identity of the two types of bacteria suggested that the plague microbe veered onto its own evolutionary pathway.4 Ironically, University ...
