恶性疟原虫abstrakt同源基因的克隆及DEAD盒家族蛋白的序列分析

DEAD盒蛋白家族的ATP依赖性的RNA解旋酶类参与细胞内几乎所有的RNA代谢过程 ,在几乎所有生物的细胞生长发育过程中扮演着众多不可或缺的角色。在本实验中 ,通过PCR和探针杂交相结合的筛选方法 ,筛选恶性疟原虫 (Plasmodiumfalciparum)的基因组文库 ,克隆了FH1F———abstrakt同源基因的完整序列。通过搜索已经完成测序的恶性疟原虫基因组数据库 ,推测FH1F序列定位在第 5条染色体上。FH1F全长2 80 4bp,包含一个 1 1 6 1bp的完整阅读框 ,编码一个由 386个氨基酸组成的蛋白。对FH1F蛋白序列用BlastP进行搜索和分析以及用DNAStar与许多典型的DEAD盒蛋白序列进行比对分析 ,结果均提示FH1F蛋白应该是DEAD盒家族的一个Abstrakt蛋白。另一方面 ,用DNAStar对已知所有完整的DEAD盒蛋白进行详细的序列分析以及用Mega对这些序列进行系统发育研究的结果都显示 :DEAD盒家族的蛋白聚类成为若干不同的亚群 ;与DEAD盒蛋白的一般保守序列相比 ,Abstrakt,eIF 4A ,Vasa ,P6 8等不同亚群的DEAD盒蛋白在保守区具有各自不同的结构特征。本文对不同的DEAD盒蛋白的结构特征进行了总结并试图给出不同亚群分类上的结构标准 ,对Abstrakt蛋白在本应高度保守的位点上异常于其它DEAD盒蛋白的氨基酸残基的取代也进行了相关的初步分析

Molecular cloning of a putative abstrakt gene from Plasmodium falciparum and sequence analysis of different DEAD-box proteins

The ATP dependent RNA helicases of the DEAD box family, involved in almost every cellular process of RNA metabolism, play many essential roles during cell development and growth in almost all organisms. In this study, FH1F *** , the full length gene of a putative Abstrakt, was isolated by screening the genomic library of Plasmodium falciparum. FH1F was inferred located in the chromosome 5 in the whole genome. FH1F is composed of 2 804 bp and encodes a predicted protein of 386 aa. Alignment analysis of the predicted protein sequence with many typical DEAD box proteins suggested FH1F protein was an Abstrakt of DEAD box family. By phylogenetic analysis we realized that DEAD box proteins assembled into different subgroups. Then we listed different organization of conserved motifs in Abstrakt, eIF 4A, Vasa, P68 proteins as compared to the general DEAD box protein consensus, and pointed out the novel residue substitutions in Abstrakt proteins in the highly conserved positions. Our analysis will be important for providing general insights into the structural characteristics of different DEAD-box proteins.