Abstact

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 A resolution and has been refined to a crystallographic R-factor of 17.0%. The enzyme is trimeric and displays the left-handed parallel beta-helix (L beta H) 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 L beta H domain.