Phylogenetic tree showing relationship between mce -linked ATPases and mycobacterial orthologs. ATPases encoded within mce operons in Actinomycetales species are colored blue; those in Gram-negative bacterial mce operons are colored green. The sequences most similar to nfa51100, SAV5902 and SCO2422 (indicated in bold), in the Actinomycetales genomes listed in Table 1, were identified by BLASTP searches and included in the tree. All of the best hits from mycobacterial species cluster within the Mkl family and are colored red. For comparison, sequences of all M. tuberculosis H37Rv ATPases of ABC uptake transporters were included . All of the top hits from Actinomycetales that do not possess mce operons are rooted among these non-mce-linked ATPases, as are all of the second hits from mycobacterial species. ORFs are designated by (UniProt gene name | protein name).