Crystal structure of Pseudomonas aeruginosa SPM-1 provides insights into variable zinc affinity of metallo-beta-lactamases.

Metallo-beta-lactamases (mbetals) confer broad-spectrum resistance to beta-lactam antibiotics upon host bacteria and escape the action of existing beta-lactamase inhibitors. SPM-1 is a recently discovered mbetal that is distinguished from related enzymes by possession of a substantial central insertion and by sequence variation at positions that maintain active site structure. Biochemical data show SPM-1 to contain two Zn2+ sites of differing affinities, a phenomenon that is well documented amongst mbetals but for which a structural explanation has proved elusive.

Biochemical characterization of the acquired metallo-beta-lactamase SPM-1 from Pseudomonas aeruginosa.

SPM-1 is a new metallo-beta-lactamase recently identified in Pseudomonas aeruginosa strain 48-1997A, isolated in Sao Paulo, Brazil. Kinetic analysis demonstrated that SPM-1 has a broad hydrolytic profile across a wide range of beta-lactam antibiotics. Considerable variation was observed within the penicillin, cephalosporin, and carbapenem subfamilies; however, on the whole, SPM-1 appears to preferentially hydrolyze cephalosporins.

Molecular characterization of SPM-1, a novel metallo-beta-lactamase isolated in Latin America: report from the SENTRY antimicrobial surveillance programme.

The gene encoding the metallo-beta-lactamase SPM-1 was cloned from a genomic library of Pseudomonas aeruginosa strain 48-1997 A. The insert carrying spm-1 possessed a GC content of 47%, indicating that it is of non-Pseudomonas origin. Upstream of spm-1 there is a small open reading frame (ORF), which is homologous to the LysR family of proteins (69% identity to the LysR protein from Salmonella enterica serovar Typhimurium).