Division of Applied Life Science (BK21 Program) and PMBBRC, Gyeongsang National University, Jinju, Republic of Korea.
FEBS Lett. 2012 Sep 21;586(19):3493-9. doi: 10.1016/j.febslet.2012.08.002. Epub 2012 Aug 10.
Based on the fact that the amino acid sequence of sulfiredoxin (Srx), already known as a redox-dependent sulfinic acid reductase, showed a high sequence homology with that of ParB, a nuclease enzyme, we examined the nucleic acid binding and hydrolyzing activity of the recombinant Srx in Arabidopsis (AtSrx). We found that AtSrx functions as a nuclease enzyme that can use single-stranded and double-stranded DNAs as substrates. The nuclease activity was enhanced by divalent cations. Particularly, by point-mutating the active site of sulfinate reductase, Cys (72) to Ser (AtSrx-C72S), we demonstrate that the active site of the reductase function of AtSrx is not involved in its nuclease function.
基于已知的作为一种依赖于氧化还原的亚磺酸还原酶的硫氧还蛋白（Srx）的氨基酸序列与核酸酶 ParB 具有高度序列同源性这一事实，我们检测了拟南芥（AtSrx）中重组 Srx 的核酸结合和水解活性。我们发现 AtSrx 作为一种核酸酶，能够以单链和双链 DNA 作为底物。该核酸酶活性可被二价阳离子增强。特别是，通过定点突变亚磺酸还原酶的活性位点半胱氨酸（Cys72）为丝氨酸（AtSrx-C72S），我们证明了 AtSrx 的还原酶活性的活性位点不参与其核酸酶功能。
