<p> This entry represents a subset of the DapA (dihydrodipicolinate synthase) family which has apparently evolved a separate function. The product of DapA, dihydrodipicolinate, results from the non-enzymatic cyclization and dehydration of 6-amino-2,4-dihydroxyhept-2-ene-1,7-dioic acid, which is different from the substrate of this reaction only in the presence of the amino group. In the absence of this amino group, and running the reaction in the opposite direction, the reaction corresponds to the HpaI aldolase component of the 4-hydroxyphenylacetic acid catabolism pathway (see <db_xref db="INTERPRO" dbkey="IPR012689"/>). At present, this variant of DapA is found only in <taxon tax_id="221109">Oceanobacillus iheyensis HTE831</taxon> and <taxon tax_id="262724">Thermus thermophilus</taxon> (strain HB27/ATCC BAA-163/DSM 7039). In both of these cases, one or more other DapA genes can be found and the members of this family are found in the operon for 4-hydroxyphenylacetic acid catabolism.</p> 2,4-dihydroxyhept-2-ene-1,7-dioic acid aldolase variant