Nitrilase superfamily, including nitrile- or amide-hydrolyzing enzymes and amide-condensing enzymes
This superfamily (also known as the C-N hydrolase superfamily) contains hydrolases that break carbon-nitrogen bonds; it includes nitrilases, cyanide dihydratases, aliphatic amidases, N-terminal amidases, beta-ureidopropionases, biotinidases, pantotheinase, N-carbamyl-D-amino acid amidohydrolases, the glutaminase domain of glutamine-dependent NAD+ synthetase, apolipoprotein N-acyltransferases, and N-carbamoylputrescine amidohydrolases, among others. These enzymes depend on a Glu-Lys-Cys catalytic triad, and work through a thiol acylenzyme intermediate. Members of this superfamily generally form homomeric complexes, the basic building block of which is a homodimer. These oligomers include dimers, tetramers, hexamers, octamers, tetradecamers, octadecamers, as well as variable length helical arrangements and homo-oligomeric spirals. These proteins have roles in vitamin and co-enzyme metabolism, in detoxifying small molecules, in the synthesis of signaling molecules, and in the post-translational modification of proteins. They are used industrially, as biocatalysts in the fine chemical and pharmaceutical industry, in cyanide remediation, and in the treatment of toxic effluent. This superfamily has been classified previously in the literature, based on global and structure-based sequence analysis, into thirteen different enzyme classes (referred to as 1-13). This hierarchy includes those thirteen classes and a few additional subfamilies. A putative distant relative, the plasmid-borne TraB family, has not been included in the hierarchy.
Structure:3DLA_C; Mycobacterium tuberculosis glutamine-dependent NAD+ synthetase (GAT_Gln-NAD-synth) monomer bound with DON inhibitor in the GAT domain, contacts calculated at 4 A. - View structure with Cn3D
Comment:M. tuberculosis GAT_Gln-NAD-synth is a bifunctional enzyme having a NAD+ synthetase domain in addition to this GAT domain.