Characterization and comparative analysis of a second thermonuclease from Staphylococcus aureus
Characterization and comparative analysis of a second thermonuclease from Staphylococcus aureus
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金黄色葡萄球菌第二种热核酸酶的表征和比较分析
DOI：
10.1016/j.micres.2012.09.003
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发表时间：
2013-01-01
影响因子：
6.7
通讯作者：
Shi, Xianming
中科院分区：
文献类型：
--
作者：
Hu, Yu;Meng, Jianghong;Shi, Xianming
葡萄球菌核酸酶（Staphylococcal nuclease，简称Nucl）是一种重要的毒力因子，也是金黄色葡萄球菌（Staphylococcus aureus）的特异性标志物。第二种功能性热稳定核酸酶（这里称为Nuc 2）在S.序列比对和系统发育分析表明，Nuc 2在葡萄球菌中比Nuc 1更为保守，重组Nuc 2在酶谱分析中显示出核酸酶活性，并能降解多种类型的核酸。Nuc 2的最适反应温度为50 ℃，最适pH为10。在Ca 2+（0.05 mM）、Mg 2+（0.5 mM）、二硫苏糖醇、β-巯基乙醇、TritonX-100、Tween-20和尿素的存在下，Nuc 2的酶活性受到刺激;然而，当暴露于重金属（如Zn 2+和Mn 2+）以及EDTA或SDS的存在下时，活性急剧下降。与Nucl相比，Nuc 2表现出较弱的活性、较低的热稳定性和对这些化学试剂的不同敏感性，这与预测的序列模式和结构的差异一致。此外，还获得了一株nuc 1和nuc 2双缺失突变株。aureus和相应的互补实验表明nuc 1在S.金黄色。(C)2012 Elsevier GmbH. All rights reserved.
Staphylococcal nuclease (here termed as Nucl) is considered an important virulence factor and a unique marker widely used in the detection of Staphylococcus aureus. A second functional thermostable nuclease (here termed as Nuc2) in S. aureus was characterized after recombinant expression in Escherichia coll. Sequence alignment and phylogenetic analysis revealed that Nuc2 was a more conserved protein in the staphylococci group compared with Nucl. Recombinant Nuc2 showed nuclease activity in the zymogram test and was able to degrade various types of nucleic acids. The optimal reaction temperature and pH for Nuc2 were 50 C and pH 10, respectively. The enzymatic activity of Nuc2 was stimulated in the presence of Ca2+ (0.05 mM), Mg2+ (0.5 mM), dithiothreitol, beta-mecaptoethanol, TritonX-100, Tween-20, and urea; however, activity decreased sharply when exposed to heavy metals such as Zn2+ and Mn2+, and in the presence of EDTA or SDS. Nuc2 showed weaker activity, lower thermostability and different sensitivity to these chemical agents compared with Nucl, which was consistent with differences in the sequence pattern and structure predicted. Furthermore, a nuc1 and nuc2 double deletion mutant of S. aureus and respective complementation experiments suggest a major role for nuc1 in terms of thermonuclease activity in S. aureus. (C) 2012 Elsevier GmbH. All rights reserved.