InterPro domain: IPR006439

The Haloacid Dehalogenase (HAD) superfamily is defined by the presence of three short catalytic motifs [ 1 ]. The subfamilies are defined [ 2 ] based on the location and the observed or predicted fold of a so-called capping domain [ 3 ], or the absence of such a domain. Subfamily I consists of sequences in which the capping domain is found in between the first and second catalytic motifs. Subfamily II consists of sequences in which the capping domain is found between the second and third motifs. Subfamily III sequences have no capping domain in either of these positions.

The Subfamily IA and IB capping domains are predicted by PSI-PRED to consist of an alpha helical bundle. Subfamily IA and IB are separated based on an apparent phylogenetic bifurcation. Of the three motifs defining the HAD superfamily, the third has three variant forms: (1) hhhhsDxxx(x)D, (2) hhhhssxxx(x)D and (3) hhhhDDxxx(x)s where _s_ refers to a small amino acid and _h_ to a hydrophobic one. All three of these variants are found in subfamily IA.

NOTE: Three variant models were created by TIGRFAMs with some overlap among them to cover subfamily IA. This serves the purpose of eliminating the overlap with models of more distantly related HAD subfamilies caused by an overly broad single model.

1. Computer analysis of bacterial haloacid dehalogenases defines a large superfamily of hydrolases with diverse specificity. Application of an iterative approach to database search. J. Mol. Biol. 244, 125-32
2. MDP-1 is a new and distinct member of the haloacid dehalogenase family of aspartate-dependent phosphohydrolases. Biochemistry 40, 12704-11
3. The crystal structure of bacillus cereus phosphonoacetaldehyde hydrolase: insight into catalysis of phosphorus bond cleavage and catalytic diversification within the HAD enzyme superfamily. Biochemistry 39, 10385-96