title: Biochemical characterization of two DNA ligases from Deinococcus radiodurans.
abstract: Two genes encoding a NAD(+)-dependent DNA ligase (LigA) and an ATP-dependent DNA ligase (LigB) were identified in the genome of the extremely radioresistant bacterium, Deinococcus radiodurans (DR). The recombinant enzymes expressed in Escherichia coli, were purified to homogeneity and characterized. The optimal temperature and pH value of the two DNA ligases were 60 ( degrees )C and 7.0, respectively. Their optimal concentration of MgCl(2) was 5mM. Their half-lifes of heat inactivation at 100 ( degrees )C were about 3 min and 5 min, respectively. In addition, the results showed that DRLigB displayed higher activity than DRLigA at stick and blunt ended joining of DNA, indicating that DRLigB is a key DNA ligase of D. radiodurans in DNA recombination and double-strand break repair.
authors.affiliation: Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear-Agricultural Sciences, Zhejiang University, 310029, China.
authors.forename: Donghai
authors.initials: D
authors.lastname: Le
authors.forename: Xiaoting
authors.initials: X
authors.lastname: Hua
authors.forename: Lifen
authors.initials: L
authors.lastname: Huang
authors.forename: Guanjun
authors.initials: G
authors.lastname: Gao
authors.forename: Huiming
authors.initials: H
authors.lastname: Lu
authors.forename: Zhenjian
authors.initials: Z
authors.lastname: Xu
authors.forename: Bing
authors.initials: B
authors.lastname: Tian
authors.forename: Yuejin
authors.initials: Y
authors.lastname: Hua
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000235:genetics / Q000378:metabolism*; D034301:Deinococcus / Q000201:enzymology* / Q000235:genetics; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D011994:Recombinant Proteins / Q000378:metabolism; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D011088:DNA Ligases; D000072481:DNA Ligase ATP; C120640:DNA ligase (NAD)