title: Characterization of a new TEM-derived beta-lactamase produced in a Serratia marcescens strain.
abstract: A natural TEM variant beta-lactamase was isolated from an epidemic strain of Serratia marcescens. Nucleotide gene sequencing revealed multiple point mutations located in the 42-to-44 tripeptide and positions 145 to 146, 178, and 238. In addition, a glutamic acid 212 deletion was also found. The purified enzyme was studied from a kinetic point of view, revealing the highest catalytic efficiency (k[cat]/Km) values for ceftazidime and aztreonam compared with the TEM-1 prototype enzyme. The in vitro resistance correlated with kinetic parameters, and the enzyme also mediated resistance to some penicillins and an ampicillin-clavulanic acid combination. The mutational and kinetic changes are discussed in relation to the three-dimensional crystallographic structure of the wild-type TEM-1 enzyme.
authors.affiliation: Dipartimento di Scienze e Tecnologie Biomediche, Cattedra di Chimica Biologica, Facoltà di Medicina e Chirurgia, Università degli Studi dell'Aquila, L'Aquila, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Perilli
authors.forename: A
authors.initials: A
authors.lastname: Felici
authors.forename: N
authors.initials: N
authors.lastname: Franceschini
authors.forename: A
authors.initials: A
authors.lastname: De Santis
authors.forename: L
authors.initials: L
authors.lastname: Pagani
authors.forename: F
authors.initials: F
authors.lastname: Luzzaro
authors.forename: A
authors.initials: A
authors.lastname: Oratore
authors.forename: G M
authors.initials: GM
authors.lastname: Rossolini
authors.forename: J R
authors.initials: JR
authors.lastname: Knox
authors.forename: G
authors.initials: G
authors.lastname: Amicosante
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D003461:Crystallography; D004352:Drug Resistance, Microbial; D007700:Kinetics; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010406:Penicillins / Q000494:pharmacology; D012706:Serratia marcescens / Q000201:enzymology*; D001618:beta-Lactamases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D010406:Penicillins; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1