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. The highest k(cat/)K(m) ratios (in micromolar per second) overall were observed for this subgroup. The hydrolytic profile of SPM-1 bears the most similarity to that of the metallo-beta-lactamase IMP-1, yet for the most part, SPM-1 has k(cat)/K(m) values higher than those of IMP-1. Zinc chelator studies established that progressive inhibition of SPM-1 by EDTA, dipicolinic acid, and 1-10-o-phenanthroline demonstrated a biexponential pattern in which none of the chelators completely inhibited SPM-1. A homology model of SPM-1 was developed on the basis of the IMP-1 crystal structure, which showed the protein folding and active-site structure characteristic of metallo-beta-lactamases and which provides an explanation for the kinetic profiles observed.
Murphy
Tanya A
TA
Department of Pathology and Microbiology, University of Bristol, Bristol BS8 1TD, United Kingdom. tanya.murphy@bristol.ac.uk
Simm
Alan M
AM
Toleman
Mark A
MA
Jones
Ronald N
RN
Walsh
Timothy R
TR
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa; D001618:beta-Lactamases / Q000235:genetics / Q000302:isolation & purification* / Q000494:pharmacology; D047090:beta-Lactams
D000900:Anti-Bacterial Agents; D047090:beta-Lactams; C409201:beta-lactamase IMP-1; C476155:beta-lactamase SPM-1, Pseudomonas aeruginosa; D001618:beta-Lactamases