Alignment of IMPases. The M. tuberculosis H37RvIMPases were aligned using ClustalW. (A) Complete sequences. Motifs shown in bold; (B) Prosite motifs: '*' identical residues in all sequences; ':' conserved substitutions; '.' semi-conserved substitutions. Sequences were obtained from http://genolist.pasteur.fr/TubercuList/. Reported Prosite motifs are 1 (N-terminal; PS00629): [FWV]-x(0,1)- [LIVM]-D-P- [LIVM]-D- [SG]- [ST]-x(2)- [FY]-x- [HKRNSTY]; and 2 (C-terminal; PS00630): [WYV]-D-x- [AC]- [GSA]- [GSAPV]-x- [LIVFACP]- [LIVM]- [LIVAC]-x(3)- [GH]- [GA]. Residues that are not encompassed by these motifs are in bold italics. Arrows indicate putative metal binding aspartate and isoleucine residues reported for human IMPase . The underlined residue shows the aspartate mutated in this study, which is equivalent to mutations introduced into the E. coli and human proteins (see main text).