This is the N-terminal domain found in o-succinylbenzoate synthase (OSBS) enzymes (EC:4.2.1.113). Like other members of the enolase superfamily, OSBS enzymes are composed of a C-terminal catalytic (beta/alpha)7beta-barrel domain Pfam:PF00113 and an N-terminal capping domain with an alpha+beta fold that is found in the enolase superfamily [1]. This domain is different from other enolase super family N-terminal domains such as Pfam:PF03952. This actino-bacterial N-terminal domain lacks the prototypical first two helices of the enolase capping domains. Structural analysis of T. fusca OSBS reveals that this is compensated for with an extra helix appended to the C-terminus [2].

1: Residues required for activity in Escherichia coli o-succinylbenzoate synthase (OSBS) are not conserved in all OSBS enzymes. Zhu WW, Wang C, Jipp J, Ferguson L, Lucas SN, Hicks MA, Glasner ME; Biochemistry. 2012;51:6171-6181. PMID:22775324

2: Divergent evolution of ligand binding in the o-succinylbenzoate synthase family. Odokonyero D, Ragumani S, Lopez MS, Bonanno JB, Ozerova ND, Woodard DR, Machala BW, Swaminathan S, Burley SK, Almo SC, Glasner ME; Biochemistry. 2013;52:7512-7521. PMID:24060347