metallo-beta-lactamases; subclasses B1 and B2 and related proteins; 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. Subclass B1 enzymes are most active with two zinc ions bound in the active site, and have a broad-spectrum substrate profile. B1 MBls include chromosomally-encoded MBLs such as Bacillus cereus BcII, Bacteroides fragilis CcrA, and Elizabethkingia meningoseptica (Chryseobacterium meningosepticum) BlaB and acquired MBLs including IMP-1, VIM-1, VIM-2, GIM-1, NDM-1 and FIM-1. B2 MBLs have a narrow substrate profile that includes carbapenems, and they are active with one zinc ion bound in the Asp-Cys-His site, binding of a second zinc ion in the modified 3H site (Asn-His-His) inhibits catalysis. B2 MBLs include Aeromonas hydrophyla CphA, Aeromonas veronii ImiS, and Serratia fonticola Sfh-I.
Jiyao W et al.(2023). "The conserved domain database in 2023.",