Marine Biotechnology Research Center, Korea Ocean Research and Development Institute, Ansan, Seoul, Korea.
FEMS Microbiol Lett. 2009 Nov;300(1):68-74. doi: 10.1111/j.1574-6968.2009.01766.x. Epub 2009 Aug 24.
The TON_0002 gene, which is in close proximity to the DNA polymerase locus in Thermococcus onnurineus NA1, has been shown to encode an inorganic pyrophosphatase. Its genomic position and function suggest a role for pyrophosphate hydrolysis during DNA polymerization. This is the first report of an inorganic pyrophosphatase belonging to the haloacid dehalogenase superfamily, in which unique residues in motif I and II have been replaced with Trp and Gly, respectively. The optimum pyrophosphatase activity of the recombinant enzyme occurred at pH 6, and it displayed an absolute dependence on divalent metal ions, among which Ni(2+) was the most efficient. The site-specific mutation of the Gly residue in motif II to Ala or Ser residue exhibited only a slight change in the enzymatic activity and the K(m) value.
TON_0002 基因与 Thermococcus onnurineus NA1 的 DNA 聚合酶位点紧密相邻，已被证明编码无机焦磷酸酶。其基因组位置和功能表明在 DNA 聚合过程中焦磷酸盐水解的作用。这是属于 haloacid dehalogenase 超家族的无机焦磷酸酶的首次报道，其中特征 I 和 II 中的独特残基分别被 Trp 和 Gly 取代。重组酶的最适焦磷酸酶活性出现在 pH6 时，并且它表现出对二价金属离子的绝对依赖性，其中 Ni(2+) 是最有效的。特征 II 中 Gly 残基的定点突变到 Ala 或 Ser 残基仅使酶活性和 K(m) 值略有变化。
