phosphatase, similar to Bacillus subtilis MtnX; belongs to the haloacid dehalogenase-like superfamily
Bacillus subtilis recycles two toxic byproducts of polyamine metabolism, methylthioadenosine and methylthioribose, into methionine by a salvage pathway. The sixth reaction in this pathway is catalyzed by B. subtilis MtnX: the dephosphorylation of 2- hydroxy-3-keto-5-methylthiopentenyl-1-phosphate (HKMTP- 1-P) into 1,2-dihydroxy-3-keto-5-methylthiopentene. The hydrolysis of HK-MTP-1-P is a two-step mechanism involving the formation of a transiently phosphorylated aspartyl intermediate. Members of this family belong to the haloacid dehalogenase-like (HAD) hydrolases, a large superfamily of diverse enzymes that catalyze carbon or phosphoryl group transfer reactions on a range of substrates, using an active site aspartate in nucleophilic catalysis. Members of this superfamily include 2-L-haloalkanoic acid dehalogenase, azetidine hydrolase, phosphonoacetaldehyde hydrolase, phosphoserine phosphatase, phosphomannomutase, P-type ATPases and many others. HAD hydrolases are found in all three kingdoms of life, and most genomes are predicted to contain multiple HAD-like proteins. Members possess a highly conserved alpha/beta core domain, and many also possess a small cap domain, the fold and function of which is variable. HAD hydrolases are sometimes referred to as belonging to the DDDD superfamily of phosphohydrolases.