Aspartate-semialdehyde dehydrogenase signature

Aspartate-semialdehyde dehydrogenase (EC 1.2.1.11) (ASD) catalyzes the second step in the common biosynthetic pathway leading from Asp to diaminopimelate and Lys, to Met, and to Thr; the NADP-dependent reductive dephosphorylation of L-aspartyl phosphate to L-aspartate-semialdehyde. In bacteria and fungi, ASD is a protein of about 40 Kd (340 to 370 residues) whose sequence is not extremely well conserved [1]. A conserved cysteine residue has been implicated as important for the catalytic activity [2].

The region of conservation around the active site residue is too small to be used as as signature pattern. We have used another more conserved region, located in the last third of the sequence, and which contains both a conserved cysteine as well as an histidine.