决登伟 桑雪莲 舒波 刘丽琴 王一承 石胜友

摘 要 通过生物信息学方法，从玉米基因组中得到1个泛素结合酶家族基因序列，将其命名为ZmUBC-76。该基因序列开放阅读框为2 589 bp，编码的蛋白具有862个氨基酸，其分子量为98.91 ku，理论等电点为8.07。预测定位于细胞核。荧光定量PCR分析表明，该基因具有组织表达特异性，在根和幼果中的表达量最高，在穗丝中表达最低。非生物胁迫表达分析结果表明：在盐胁迫和干旱胁迫下，ZmUBC-76的表达呈逐渐下降趋势，在处理24 h时达到最低；在低温胁迫时，ZmUBC-76的表达量未出现显著变化。上述结果表明，ZmUBC-76可能参与了植物对盐和干旱胁迫的响应。

关键词 玉米；泛素结合酶基因；干旱；低温；盐胁迫

中图分类号 Q78 文献标识码 A

Functional Analysis of a Ubiquitin-conjugating

Enzyme Gene ZmUBC-76 in Maize

JUE Dengwei， SANG Xuelian， SHU Bo， LIU Liqin， WANG Yicheng， SHI Shengyou*

South Subtropical Crops Research Institute， CATAS / Key Laboratory of Tropical Fruit Biology，

Ministry of Agriculture， Zhanjiang， Guangdong 524091， China

Abstract In the present study， a ubiquitin-conjugating family gene was identified and designated as ZmUBC-76， in maize genome by using the bioinformatics method. The ORF of ZmUBC-76 is 2 589 bp that encodes 862 amino acid residues with an estimated molecular mass of 98.91 ku and a calculated pI of 8.07. Meanwhile， Plant-mPLoc predicted that the ZmUBC-76 protein was localized in the nucleus. Real-time qPCR assay showed that the highest expression level of ZmUBC-76 occurred in the roots and young seeds， and the lowest of ZmUBC-76 occurred in the silks， which meant ZmUBC-76 appeared to have a tissue-specific expression pattern. The expression levels of ZmUBC-76 under different abiotic stress were also analyzed by real-time qPCR. The results showed that the expression of ZmUBC-76 decreased at the test time by salt and drought stress， and reached the lowest level at 24 h. However， the expression levels of ZmUBC-76 under low temperature stress had no significant change. These results indicated that ZmUBC-76 could be involved in plant response to salt and drought stress.

Key words Maize； ubiquitin-conjugating enzyme gene； drought； low temperature； salt stress

doi 10.3969/j.issn.1000-2561.2017.08.021

泛素化广泛地存在于真核细胞中，从单细胞的酵母到高等生物人类。泛素-蛋白酶体途径（Ubiquitin-proteasome pathway，UPP）是细胞内蛋白质选择性降解的重要途径。蛋白的泛素化主要通过泛素活化酶（E1）、泛素结合酶（E2）和泛素-蛋白连接酶（E3）共同介导完成。通过3种酶先后与靶蛋白结合形成1条多泛素链，将底物蛋白泛素化，使靶蛋白被26S蛋白酶所识别和降解，从而实现对多种代谢过程的调节[1-2]。其中，泛素结合酶（E2）是泛素-蛋白酶体途径的重要组成部分，对泛素化修饰的特异性和精确时空性起关键作用[3]。

目前，在酵母（Saccharomyces cerevisiae）[4]、拟南芥[5]、水稻[6]和香蕉[7]等多种真核生物中都有关于E2蛋白的报道。对植物泛素结合酶功能的研究主要集中在DNA修复、生长发育和抗逆境胁迫响应等方面[8-9]。比如，在拟南芥中发现37个E2，这些E2蛋白在拟南芥的生长、发育及响应逆境胁迫中起到重要的作用[5]。……