胡军华;李永胜;姚廷山;赵永安;周娜;周常勇;

• 1:西南大学柑桔研究所·柑桔工程技术中心·西南果树科学观测实验站
• 2:西南大学园艺园林学院

摘要(Abstract)：

【目的】研究柑橘溃疡病菌(Xac)纤维素酶的结构功能特点及其可能的作用机制。【方法】通过生物信息学分析,获得Xac纤维素酶的等电点、分子质量、信号肽、结构域和功能等特点。选取其中的Xaccel1、Xaccel3及Xaccel5基因进行克隆和表达,并对重组蛋白进行酶学分析。【结果】Xac纤维素酶共有22个蛋白,分成11组;Xac纤维素酶多在350aa左右,63.6%具有信号肽;具有GH5、GH8、GH9及GH12 4个糖基水解酶家族模块,具有GH5模块的纤维素酶占Xac纤维素酶的54.5%。此外,Xac的纤维素酶还具有CMB2、Cel D_N、TAT等功能模块。与Xanthomonas属其他纤维素酶比对发现,Xac纤维素酶在整个Xanthomonas属均有同源蛋白,与X.campestris pv.vesicatoria(Xcv)的纤维素酶同源性最高,所具有的功能性结构域的种类和个数比较接近。重组蛋白Xaccel1和Xaccel3为内切葡聚糖苷酶,它们的主要的作用方式为随机地断裂各底物的β-1,4糖苷键,对相应的糖进行降解。Xaccel5也具有内切葡聚糖苷酶活性,仅能作用于底物的还原末端的β-1,4糖苷键。3个纤维素酶具体的作用机制还需进一步的试验证明。【结论】Xac纤维素酶中Xaccel1(具有GH12)可以利用多种糖类,与Xaccel3(GH5/CBM2)均为内切葡聚糖苷酶,主要的作用方式为随机地断裂各底物的β-1,4糖苷键,对相应的糖进行降解。Xaccel5(GH5)也具有内切葡聚糖苷酶活性,仅能作用于底物的还原末端的β-1,4糖苷键。

关键词(KeyWords)： 柑橘溃疡病菌;纤维素酶;酶学机制;生物信息学分析

Abstract:

Keywords:

基金项目(Foundation): 农业部行业公益项目(201003067);; 重庆市科技支撑示范工程(cstc2014fazkjcsf0075);; 教育部西南大学项目(XDJK2013C104)

作者(Authors): 胡军华;李永胜;姚廷山;赵永安;周娜;周常勇;

DOI: 10.13925/j.cnki.gsxb.20140423

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