Protein sequences of linked genes are highly conserved in two bacterial species

It has been shown that proteins encoded by linked genes have similar rates of evolution and that clusters of essential genes are found in regions with low recombination rates. We show here that proteins encoded by linked genes in two closely related bacterial species, namely Escherichia coli K12 and Salmonella typhimurium LT2, evolve more slowly when compared with proteins encoded by genes that are not linked as assessed by protein sequence similarity. The proteins encoded by the identified linked genes share an average sequence identity of 82.5% compared with a 46.5% identity of proteins encoded by genes that are not linked.