LAUSR

Abstract OmpA-like domain proteins bind to peptidoglycan by interacting with the d -amino acid moiety of meso -diaminopimelate in peptidoglycan, but it is still not clear how this domain recognizes the d -amino region of peptidoglycan. To study their d -stereoisomer preference, we solved the crystal structures of the OmpA-like domains of Acinetobacter baumannii peptidoglycan-associated lipoprotein (AbPal) in complex with d - or l -diaminopimelate. Our results reveal that these domains can bind both enantiomers of diaminopimelate with a greater affinity for d -diaminopimelate. The crystal structures of wild-type AbPal in complex with meso -diaminopimelate and mutant AbPal in complete with the l l -diaminopimelate ligand suggests that the Tyr85 residue of AbPal is an important determinant for this d -amino acid moiety preference. Our findings provide a basis for the development of antibacterial agents that inhibit interactions between PGN and OmpA-like domains and disrupt the stability of cell walls of gram-negative bacteria.