title: Biochemical characterization of an ATP-dependent DNA ligase from the hyperthermophilic crenarchaeon Sulfolobus shibatae.
abstract: A gene encoding a putative ATP-dependent DNA ligase was identified in the genome of the hyperthermophilic archaeon Sulfolobus shibatae and expressed in Escherichia coli. The 601 amino acid recombinant polypeptide was a monomeric protein capable of strand joining on a singly nicked DNA substrate in the presence of ATP ( K(m)=34 micro mu) and a divalent cation (Mn(2+), Mg(2+), or Ca(2+)). dATP was partially active in supporting ligation catalyzed by the protein, but GTP, CTP, UTP, dGTP, dCTP, dTTP, and NAD(+) were inactive. The cloned Ssh ligase showed an unusual metal cofactor requirement; it was significantly more active in the presence of Mn(2+) than in the presence of Mg(2+) or Ca(2+). Unexpectedly, the native Ssh ligase preferred Mg(2+) and Ca(2+) rather than Mn(2+). Both native and recombinant enzymes displayed optimal nick-joining activity at 60-80 degrees C. Ssh ligase discriminated against substrates containing mismatches on the 3'-side of nick junction and was more tolerant of mismatches at the 5'-end than of those at the penultimate 5'-end. The enzyme showed little activity on a 1-nucleotide gapped substrate. This is the first biochemical study of a DNA ligase from the crenarchaeotal branch of the archaea domain.
authors.affiliation: State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080, People's Republic of China.
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Lai
authors.forename: Hongbing
authors.initials: H
authors.lastname: Shao
authors.forename: Fuying
authors.initials: F
authors.lastname: Hao
authors.forename: Li
authors.initials: L
authors.lastname: Huang
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D017104:Bacteriophage M13 / Q000235:genetics; D002413:Cations, Divalent / Q000378:metabolism; D003001:Cloning, Molecular; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D017931:DNA Primers; D004269:DNA, Bacterial / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism; D004926:Escherichia coli; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D016944:Sulfolobus / Q000201:enzymology* / Q000235:genetics; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D002413:Cations, Divalent; D017931:DNA Primers; D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D004279:DNA, Viral; D009711:Nucleotides; D011993:Recombinant Fusion Proteins; D000255:Adenosine Triphosphate; D011088:DNA Ligases; D000072481:DNA Ligase ATP