泛素活化酶是泛素-蛋白酶体途径主要成员之一，负责催化泛素蛋白酶体降解途径的第一步级联反应。本研究通过生物信息学分析，从B73玉米全基因组中鉴定出4个泛素活化酶基因，分别命名为ZmUBA1-4。4个ZmUBA基因编码氨基酸数目在1030 aa-1056 aa之间，编码蛋白分子量在114.63 kD-117.39 kD之间，等电点在5.18-5.8之间，且均含有5个内含子，蛋白二级结构预测4个基因编码的蛋白主要以α–螺旋和不规则卷曲为主；亚细胞定位预测4 个基因均定位于细胞核中。荧光定量PCR结果表明：ZmUBA1基因在根、茎、叶、雄穗、雌穗中呈现组成性表达，ZmUBA2和ZmUBA4基因在雄穗表达量最高，ZmUBA3在叶片表达量最高，呈现组织特异性表达。ZmUBA3在盐和低温胁迫上调表达，ZmUBA4在盐胁迫时下调表达，说明ZmUBA3基因可能参与玉米低温和盐胁迫的应答，ZmUBA4可能参与玉米盐胁迫应答。
英文摘要:
Ubiquitin activating enzyme is one of the main members of the ubiquitin proteasome pathway, which is responsible for the first step of the Ubiquitin-proteasome pathway(UPP). In the present study, four ubiquitin activating enzyme (UBA) genes which designated as ZmUBA1-4 were identified from the whole genome of B73 maize by using bioinformatics method. The polypeptide lengths of the ZmUBA genes ranged from 1033 aa to 1056 aa, and their predicted molecular weights ranged from 114.63 kD to 117.39 kD . The predicted pI had a range of 5.18 to 5.8, and all of the ZmUBA genes contained 5 introns. The predicted secondary structure suggested that the main structure of four proteins were alpha helix and random coil; The subcellular localization analysis showed that all of the ZmUBA proteins were located in the nucleus. Real-time qPCR assay showed that ZmUBA1 gene was co-expressed in roots, stems, leaves, male spikes and female ears, the highest expression level of ZmUBA2 and ZmUBA4 were occured in the male spikes and ZmUBA3 occured in leaves, and three genes showed tissue specific expression . The exression of ZmUBA3 was up-regulated under salt and low temperature stresses, and ZmUBA4 gene was down-regulated under salt stress, These results indicated that ZmUBA3 may be involved into plant response to salt and low temperature stresses, and ZmUBA4 only involved into plant response to salt stress.
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