擎天凤梨泛素基因的克隆与序列分析

Cloning and Sequence Analysis of Ubiquitin Gene from Guzmania

鉴于泛素与植物受高温等环境胁迫下产生的一些诱导型蛋白降解有关,本研究根据擎天凤梨Ostara早期花器的全长cDNA文库,经大规模随机测序及重叠群(contigs)内EST序列的拼接,获得了擎天凤梨多聚泛素基因全长cDNA序列(GenBank登录号:GQ890686),序列长1896bp,开放阅读框长1323bp,编码441个蛋白氨基酸残基,蛋白质分子质量为49.3kD,等电点pI为6.59。蛋白二级结构预测显示,该蛋白主要由随机卷曲、延伸链、α螺旋和β-转角组成;系统进化树分析表明与拟南芥推定的多聚泛素UBQ10(gi|23397122|gb|AAN31845.1|)亲缘关系最近;经推断它是由5个单体泛素组成的多聚泛素。本研究有助于进一步探讨该基因在低温胁迫下的反应机理以及如何采用分子调控手段增强擎天凤梨的耐低温能力。

Whereas ubiquitin was concerned with degradation of induced protein which were produced under adverse surroundings such as high-temperature, based on floral organ full length cDNA library constructed successfully in Guzmania ostara, we obtained full length cDNA sequence of ubiquitin gene by random sequencing on a large scale and EST sequences assembly in a congtig （GenBank accession No. GQ890686）. The cDNA sequence consisted of 1 896 bp and had an open reading frame （ORF） of 1 323 bp which encoded a protein of 441 amino acids residues, while the estimated molecular weight and isoelectric point of the putative protein were 49.3 kD and 6.59, respectively. Prediction of the secondary structure of the protein showed that, the protien was composed of random coil, extend strand, alpha helix and beta turn, as well as the ubiquitin gene was most near to putative polyubiquitin UBQ10 （gi｜23397122｜gb｜AAN 31845.1 ｜） in A rabidopsis thaliana based on phylogenetic tree analysis. In this research, we deduced that the ubiquitin gene obtained in guzmania should be polyubiquitin gene which was composed of five moner ubiquitins. The research was benefitial to the further discussion for exploring reaction mechanism of ubiquitin gene in low temperature stress surroundings and finding molecular regulation methods of enhancing anti-low temperature ability of guzmania.