脱水素(Dehydrins, DHNs)是高等植物胚胎发育晚期产生的一类特异多肽, 其表达累积程度与植物的发育阶段、低温、ABA和脱水信号调节等因素密切相关。为了解脱水素的结构与干旱胁迫表达累积反应, 文章从六棱大麦分离到序列全长为1 767 bp的Dhn6基因, 序列分析结果表明, 该基因含一个92 bp内含子, 90~1 759 bp为一个开放阅读框, 与裸大麦Dhn6基因(GenBank登录号: AF043091)的同源性最高, 达93.18%, 编码523个氨基酸残基的多肽, 预测蛋白质的分子量为49.68 kDa, 理论等电点为8.04。结构分析发现, 蛋白质具有3个螺旋区, 无规则卷曲构成二级结构的主要组分, 亲水氨基酸比例超过83%; 三维结构预测发现, 多肽链自身反向平行排列成松散的亲水索链, K-片段参与兼性a-螺旋结构域的形成, 意味着该脱水素具有束缚自由水、稳定细胞膜相结构的功能。实时定量RT-PCR检测结果表明, Dhn6基因的相对表达水平在干旱处理8 h快速累积, 推测DHN6在大麦对干旱胁迫的早期响应中发挥重要功能。
Dehydrins (DHNs), proteins with protective functions encoded by the late embryogenesis abundant (LEA), are differentially up-regulated at the transcriptional level under environmental stresses such as water deficit, salinity, and low temperature or in response to ABA. Data involving protein structure and expression of dehydrins could elucidate their functional roles under dehydration conditions in plants. Dhn6 gene of 1 767 bp with an intron (92 bp) in six-rowed barley, a member of LEA D11, was cloned into pMD18-T vector in the present study. It shared 93.18% identity with Hordeum vulgare ssp. vulgare (GenBank accession: AF043091), encoding a protein composed of 523 amino acid residues with the predicted molecular weight of 49.68 kDa and the theoretical isoelectric point of 8.04. Analyses of domain and structure indicated that the protein was dominantly composed of 83% hydrophillic amino acid residues, with numerous imperative curls and three loosed helixes. Three-dimensional measurement revealed that the water-soluble lipid-associating protein was attributed to its twisted cable formed by reverse paralleled chains. Moreover, the putative amphipathic α-helices formed by K-segments might play roles in protecting membrane structure in barley. Significantly, relatively high accumulations of Dhn6 gene were detected after 8 h of water deficit by real-time quantitative RT-PCR. These results possibly suggested that the accumulation of Dhn6 gene could be critical for resistant dehydration in plants.
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