Phylogenetic tree of mycobacterial Mas domain sequences. The conserved Mas domains of mycobacterial proteins listed in Table 4 were aligned and an unrooted neighbor-joining tree was computed by MEGA. Coloring corresponds to the classification scheme specified in Table 3. ORFs are designated by [gene locus name | operon number (1, 3, 4, 7) and gene position (A-D)]. Where operon orthology cannot be inferred, operons are designated: -1, -2.