title: Characterization of a recombinant (+)-γ-lactamase from Microbacterium hydrocarbonoxydans which provides evidence that two enantiocomplementary γ-lactamases are in the strain.
abstract: A two-step method, i.e., the transfer acyl analysis and then the chiral HPLC analysis, was employed in the screening of the cosmid library of Microbacterium hydrocarbonoxydans genome. Two enantiocomplementary γ-lactamase clones were found. A 40-kb cosmid showed (-)-γ-lactamase activity, and the activity was from Mhg which was reported previously according to the results of PCR identifying experiment. The 37-kb (+)-γ-lactamase cosmid was further constructed into a pUC18 plasmid library and screened by the same two-step method. A plasmid clone harboring a 1.6-kb fragment showed (+)-γ-lactamase activity. A 555-bp ORF in the 1.6-kb fragment showed high (+)-γ-lactamase activity when it was expressed under the control of T7 promoter. The coding protein showed significant homology with bacterial isochorismatase. The (+)-γ-lactamase was characterized and compared with the (-)-γ-lactamase Mhg. This is another report that two enantiocomplementary γ-lactamases are present in the same strain.
authors.affiliation: State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang, Beijing, 100101, People's Republic of China.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Wang
authors.forename: Yaxin
authors.initials: Y
authors.lastname: Zhu
authors.forename: Guogang
authors.initials: G
authors.lastname: Zhao
authors.forename: Junge
authors.initials: J
authors.lastname: Zhu
authors.forename: Sheng
authors.initials: S
authors.lastname: Wu
mesh_terms: D000192:Actinomycetales / Q000737:chemistry / Q000201:enzymology*; D000581:Amidohydrolases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D003360:Cosmids; D004926:Escherichia coli / Q000235:genetics; D015723:Gene Library; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D011994:Recombinant Proteins; D000581:Amidohydrolases; C401943:gamma-lactamase