This domain is found associated with the L,D-transpeptidase domain Pfam:PF03734. The structure of this domain has been solved and shows a mixed alpha-beta fold composed of nine beta strands and four alpha helices. This domain is usually found to be duplicated. Therefore, it seems likely that this domain acts to bind the two unlinked peptidoglycan chains and bring them into close association so they can be cross linked by the transpeptidase domain (Bateman A pers. observation).

1: Crystal structure of a novel beta-lactam-insensitive peptidoglycan transpeptidase. Biarrotte-Sorin S, Hugonnet JE, Delfosse V, Mainardi JL, Gutmann L, Arthur M, Mayer C; J Mol Biol. 2006;359:533-538. PMID:16647082