Stenotrophomonas maltophilia L1, Pseudomonas otitidis POM-1 and related metallo-beta-lactamases, subclass B3; MBL-fold metallo-hydrolase domain
MBLs (class B of the Ambler beta-lactamase classification) are a diverse group of metallo-enzymes that are capable of catalyzing the hydrolysis of a wide range of beta-lactam antibiotics. MBLs have been divided into three subclasses B1, B2 and B3, based on sequence/structural relationships and substrates, with the B1 and B2 MBLs being most closely related to each other. This subgroup of L1- and Pom-1-like MBLs belongs to the B3 subclass. Subclass B3 enzymes are most active with two zinc ions bound in the active site, and have a broad-spectrum substrate profile. These B3 enzymes have a modified Zn2/DCH site (Asp-His-His).