Purification, characterization and functional analysis of asparagines synthetase encoding by ste10 gene in Ebosin biosynthesis of Streptomyces sp 139
Purification, characterization and functional analysis of asparagines synthetase encoding by ste10 gene in Ebosin biosynthesis of Streptomyces sp 139
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链霉菌 139 的 ste10 基因编码的天冬酰胺合成酶在 Ebosin 生物合成中的纯化、表征和功能分析
DOI：
10.1016/j.enzmictec.2008.01.022
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发表时间：
2008-06-05
影响因子：
3.4
通讯作者：
Li, Yuan
中科院分区：
文献类型：
--
作者：
Bai, Liping;Jiang, Rong;Li, Yuan
链霉菌产生埃博菌素。139是一种新型的具有药用活性的胞外多糖。本文介绍了一种可能的EBosin生物合成基因ste10的功能研究。克隆并在大肠杆菌BL21中表达了Ste10蛋白，并对纯化的重组蛋白进行了鉴定。结果表明，Ste10能够催化谷氨酰胺的酰胺氮转移到天冬氨酸的侧链上，生成天冬酰胺。其Km为0.9 mm，最适温度为37℃，最适pH为7.38。Ste10基因敲除后，链霉菌突变株产生的EPS-m的单糖组成。139(ste(10-))与依博菌素相比发生了变化，但其对IL-IR的拮抗活性明显降低。根据这些结果，我们推测Ste10编码一个天冬酰胺合成酶，该酶可能在EBosin的生物合成过程中起到修饰基因的作用。(C)2008 Elsevier Inc.保留所有权利。
Ebosin produced by Streptomyces sp. 139 is a novel exopolysaccharide (EPS) with medicinal activity. This paper describes the functional study of ste10, a putative Ebosin biosynthesis gene. ste10 was cloned and expressed in Escherichia coli BL21 and the purified recombinant protein characterized. Ste10 was shown to be able of catalyzing the transfer of amide nitrogen of glutamine to the side chain of aspartate to produce asparagine. Its Km, optimum temperature and pH were determined to be 0.9 mM, 37 degrees C and 7.38, respectively. After ste10 gene knock-out, the monosaccharide composition of EPS-m produced by the mutant Streptomyces sp. 139 (ste(10-)) was found changed in comparison with that of Ebosin while its antagonist activity for IL-IR decreased significantly. Based on these results, it is concluded that ste10 codes for an asparagine synthetase which may function as a modificator gene of Ebosin during its biosynthesis. (c) 2008 Elsevier Inc. All rights reserved.