Three-Dimensional Structure of Tetrahydrodipicolinate <i>N</i>-Succinyltransferase^,

Abstract

The conversion of tetrahydrodipicolinate and succinyl-CoA to N-succinyltetrahydrodipicolinate and CoA is catalyzed by tetrahydrodipicolinate N-succinyltransferase and is the committed step in the succinylase pathway by which bacteria synthesize l-lysine and meso-diaminopimelate, a component of peptidoglycan. The X-ray crystal structure of THDP succinyltransferase has been determined to 2.2 Å resolution and has been refined to a crystallographic R-factor of 17.0%. The enzyme is trimeric and displays the left-handed parallel β-helix (LβH) structural motif encoded by the "hexapeptide repeat" amino acid sequence motif [Raetz, C. R. H., & Roderick, S. L. (1995) Science 270, 997−1000]. The approximate location of the active site of THDP succinyltransferase is suggested by the proximity of binding sites for two inhibitors; p-(chloromercuri)benzenesulfonic acid and cobalt ion, both of which bind to the LβH domain.