Conserved gene cluster at replication origins of the α-proteobacteria Caulobacter crescentus and Rickettsia prowazekii

A 30-kb region surrounding the replication origin in Caulobacter crescentus was analyzed. Comparison to the genome sequence of another alpha -proteobacterium, Rickettsia prowazekii, revealed a conserved cluster of genes (RP001, hemE, hemH, and RP883) that overlaps the established origin of replication in C. crescentus and the putative origin of replication in R prowazekii. The genes flanking this cluster differ between these two organisms. We therefore propose that this conserved gene cluster can be used to identify the origin of replication in other alpha -proteobacteria.