十字花科黑腐病菌锌吸收调控蛋白中四个半胱氨酸残基的功能分析  

Functional Analysis of Four Cysteine Residues in the Zinc Uptake Regulator of Xanthomonas campestris pathovar campestris

作　　者：唐东阶[1,2] 张雨[2] 王谜[2] 唐纪良[1,2] 臧宁[3] 

机构地区：[1]亚热带农业生物资源保护利用国家重点实验室,南宁530005 [2]广西大学生命科学与技术学院,南宁530005 [3]广西医科大学医学科学实验中心,南宁530021

出　　处：《基因组学与应用生物学》2013年第3期359-366,共8页Genomics and Applied Biology

基　　金：国家自然科学基金项目(30671142)资助

摘　　要：细菌锌吸收调控蛋白(Zur)在调控细胞锌离子平衡中起核心作用。研究发现,大肠杆菌的Zur蛋白(ZurE.coli)中半胱氨酸残基Cys93、Cys96、Cys143和Cys146是锌离子结合位点,是感受锌离子浓度和调控锌离子平衡必需的氨基酸残基。本文研究了十字花科黒腐病菌(Xanthomonas campestris pathovar campestris,简称Xcc)的Zur蛋白(ZurXcc)。序列分析结果显示,ZurXcc的Cys125、Cys128、Cys165和Cys168是与ZurE.coli的Cys93、Cys96、Cys143和Cys146相对应的半胱氨酸残基,预示它们可能是ZurXcc中的锌离子结合位点。此外,氨基酸置换结果发现,Cys125、Cys128、Cys165和Cys168中任何一个被其它氨基酸置换后,ZurXcc即丧失调控锌离子平衡的能力,证明它们是ZurXcc调控锌离子平衡必不可少的,是可能的锌离子结合位点。胞外多糖(EPS)产量和致病力检测结果还表明,ZurXcc调控锌离子平衡、EPS产生和调控致病在结构和功能上都是可以分开的。Bacteria zinc uptake regulator, Zur, plays a central role in zinc homeostasis. It has been known that the cysteine residues at positions of 93rd, 96th, 143rd, and 146th in E. coli （ZurE. coli） are the Zn^2＋-binding sites and thus are es-sential for the Zn^2＋sensing and zinc homeostasis regulation of ZurE. coli. Here, we investigate the Zur of Xanthomonas campestris pathovar campestris （Xcc） （ZurXcc）. Amino acid sequence analysis reveal that Cys^125, Cys^128, Cys^165 and Cys^168 in ZurXcc are corresponding to Cys^93, Cys^96, Cys^143 and Cys^146 of ZurE. coli respectively, suggesting that these residues may involve in binding of Zn^2＋. To challenge this hypothesis, the contribution of each of the four cysteine residues to Zur function was determined using amino acid substitution analysis. The results show that, amino acid substitution in Cys^125, Cys^128, Cys^165 and Cys^168 resulted in lost of the zinc homeostasis regulating function of ZurXcc, demonstrating that the four cysteine residues are essential for zinc homeostasis regulation of ZurXcc. More important-ly, our results demonstrated that the role of ZurXcc in the regulation of zinc homeostasis, EPS production and viru-lence of Xcc is structurally and functionally separable.

关 键 词：黄单胞菌 锌吸收调控蛋白 氨基酸置换 锌离子结合位点 锌离子平衡 

分 类 号：S432.4[农业科学—植物病理学]