title: Crystal structure of a cold-adapted class C beta-lactamase.
abstract: In this study, the crystal structure of a class C beta-lactamase from a psychrophilic organism, Pseudomonas fluorescens, has been refined to 2.2 A resolution. It is one of the few solved crystal structures of psychrophilic proteins. The structure was compared with those of homologous mesophilic enzymes and of another, modeled, psychrophilic protein. The elucidation of the 3D structure of this enzyme provides additional insights into the features involved in cold adaptation. Structure comparison of the psychrophilic and mesophilic beta-lactamases shows that electrostatics seems to play a major role in low-temperature adaptation, with a lower total number of ionic interactions for cold enzymes. The psychrophilic enzymes are also characterized by a decreased number of hydrogen bonds, a lower content of prolines, and a lower percentage of arginines in comparison with lysines. All these features make the structure more flexible so that the enzyme can behave as an efficient catalyst at low temperatures.
authors.affiliation: Chimie Biologique Structurale Laboratory, CPTS group, FUNDP, 61 rue de Bruxelles, Namur, Belgium. catherine.michaux@fundp.ac.be
authors.forename: Catherine
authors.initials: C
authors.lastname: Michaux
authors.forename: Jan
authors.initials: J
authors.lastname: Massant
authors.forename: Frédéric
authors.initials: F
authors.lastname: Kerff
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Frère
authors.forename: Jean-Denis
authors.initials: JD
authors.lastname: Docquier
authors.forename: Isabel
authors.initials: I
authors.lastname: Vandenberghe
authors.forename: Bart
authors.initials: B
authors.lastname: Samyn
authors.forename: Annick
authors.initials: A
authors.lastname: Pierrard
authors.forename: Georges
authors.initials: G
authors.lastname: Feller
authors.forename: Paulette
authors.initials: P
authors.lastname: Charlier
authors.forename: Jozef
authors.initials: J
authors.lastname: Van Beeumen
authors.forename: Johan
authors.initials: J
authors.lastname: Wouters
mesh_terms: D000595:Amino Acid Sequence; D003080:Cold Temperature; D018360:Crystallography, X-Ray; D004795:Enzyme Stability / Q000187:drug effects; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D011551:Pseudomonas fluorescens / Q000201:enzymology; D016415:Sequence Alignment; D040681:Structural Homology, Protein; D014508:Urea / Q000494:pharmacology; D001618:beta-Lactamases / Q000737:chemistry* / Q000145:classification / Q000378:metabolism*
chemical_list: D014508:Urea; D001618:beta-Lactamases