核酸酶P1的原核表达、纯化及酶学特性分析
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中央高校基本科研业务费专项 (No. QN2009070) 资助。


Prokaryotic expression, purification and enzymatic properties of nuclease P1
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Fundamental Research Funds for the Central Universities (No. QN2009070).

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    摘要:

    为了建立一种核酸酶P1 (Nuclease P1,NP1) 的原核表达纯化系统,首先采用重叠延伸PCR将22段寡核苷酸拼接,获得人工合成的NP1 基因。将其克隆至分泌型表达载体pMAL-p4X获得重组质粒pMAL-p4X-NP1,然后将重组载体转化T7 Express 和Origami B(DE3) 菌株诱导表达,利用Amylose亲和层析柱纯化获得重组蛋白,并对其活性、热稳定性和金属离子依赖性进行系统分析。SDS-PAGE结果显示,重组蛋白MBP-NP1 (Maltose binding protein-NP1) 在T7 Express 和Origami B(DE3) 菌株中均可表达,且以可溶性形式存在。活性检测表明Origami B(DE3) 菌株中获得的重组蛋白活性高于T7 Express菌株 (75.48 U/mg : 51.50?U/mg);利用蛋白酶Factor Xa切除MBP标签后,两种重组蛋白的比活力均有提高,分别为258.13 U/mg和139.20 U/mg。重组NP1表现出良好的热稳定性,80 ℃ 温浴30 min后重组酶仍具有90%以上的活力。2.0?mmol/L Zn2+对NP1有比较明显的激活作用,相同浓度的Cu2+则对该酶有强烈的抑制作用。该研究实现了NP1在大肠杆菌系统中的功能性表达,为NP1纯酶的制备提供一个替代途径。

    Abstract:

    To establish a prokaryotic expression and purification protocol for nuclease P1 (NP1), we first obtained a synthetic NP1 by splicing 22 oligonucleotides with overlapping PCR. We constructed and transformed a secretory expression vector pMAL-p4X-NP1 into Escherichia coli host strains T7 Express and Origami B (DE3) separately. Then, the recombinant NP1 was purified by amylose affinity chromatography, and its activity, thermo-stability and metal-ion dependence were investigated systematically. The results indicated that the expressed fusion proteins MBP-NP1 (Maltose binding protein-NP1) existed mainly in soluble form both in host strains T7 Express and Origami B (DE3), but the specific activity of recombinant protein from Origami B(DE3) strain was higher than T7 Express strain (75.48 U/mg : 51.50 U/mg). When the MBP-tag was cleaved by protease Factor Xa, the specific activity both increased up to 258.1 U/mg and 139.2 U/mg. The thermal inactivation experiments demonstrated that the recombinant NP1 was quite stable, and it retained more than 90% of original activity after incubated for 30 min at 80 °C. Zn2+ (2.0 mmol/L) could increase enzyme activity (to 119.1%), on the contrary, the enzyme activity was reduced by 2.0 mmol/L Cu2+ (to 63.12%). This research realized?the functional expression of NP1 in the prokaryotic system for?the?first?time, and provided an alternative pathway for NP1 preparation.

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王亚楠,魏爱云,王美艳,卫晓彬,张超,单丽伟,范三红. 核酸酶P1的原核表达、纯化及酶学特性分析[J]. 生物工程学报, 2012, 28(11): 1388-1397

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  • 收稿日期:2012-04-18
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  • 在线发布日期: 2012-11-26
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