Pasteur's genome

In the March 13 Proceedings of the National Academy of Science, May et al. report the complete sequence of the Pasteurella multocida (Pm70) genome (Proc Natl Acad Sci USA 2001, 98:3460-3465). P. multocida causes disease in birds, cattle, swine and humans, and has been studied ever since Pasteur used it in vaccine development, but the mechanisms underlying its virulence are unknown. May et al. used a shotgun strategy to sequence over 53,000 DNA fragments and assemble them into a single circular sequence of about 2.26 megabases. The Pm70 genome contains 2,014 predicted coding regions, accounting for 89% of the entire chromosome, as well as 6 rRNA operons and 57 tRNA genes. About 10% of the open reading frames are unique to P. multocida, while over half have orthologs found in closely-related Haemophilus influenza and in Escherichia coli. Comparative analysis suggests that P. multocida diverged from H. influenza around 230 million years ago and from E. coli around 680 million years ago. May et al. identified 104 putative virulence-associated genes, notably two with homology to filamentous hemagglutanin of Bordetella pertussis. Microarray analysisidentified more than 50 genes with roles in iron acquisition and metabolism.