水稻矮缩病毒第四号片段序列及编码蛋白的功能分析

SEQUENCING AND FUNCTION ANALYSIS OF THE DEDUCED PROTEIN OF RICE DWARF VIRUS GENOME SEGMENT S4

从水稻矮缩病毒(rice dwarf virus,RDV)中国福建分离物中分离出第四号片段S4的双链RNA。以人工合成的两段寡聚核苷酸链为引物,经反转录合成cDNA,然后利用PCR技术扩增了编码区cDNA,将扩增产物分成两段克隆到pGEM3Zf(-)和pBluescript上。经限制性内切酶分析,进而进行亚克隆和序列测定。将这两段克隆进行连接,得到了具有S4编码区全长cDNA的克隆。对S4编码区全长序列及其相应的氨基酸序列用DNASIS和PROSIS软件系统进行分析,结果表明:(1)S4克隆片段全长由2217个碱基组成,包含一个编码727个氨基酸的完整开放阅读框架,与RDV日本分离物S4相比,核苷酸和氨基酸序列的同源率分别为92.2％和93.9％;(2)S4编码蛋白序列含有GTP-binding模式,以及两段符合Zinc-finger模式韵序列,但这个GTP-binding模式和其中之一Zinc-finger模式并不存在于伤瘤病毒(WTV)S4编码的蛋白的序列中。

The cDNA of Rice Dwarf Virus(RDV) Fujian isolate genome segment S4 was synthesized and amplified by RT-PCR. The PCR product was cloned and sequenced. The cloned fragment is 2217bp in length. It contains one large open reading frame and encodes a polypeptide with 727 amino acids in length. It shares 92.3% and 93.9% identity with RDV S4 of Japanese isolate in terms of nucleotide and amino acid sequences, respectively. Amino acid sequences similar to a zinc-finger and GTP-binding motifs were present in the deduced protein. Considerable amino acid sequence homology was detected between genome segment S4 of RDV and WTV. One of the sequences similar to the zinc-finger motif was present in a conserved region of the polypeptide of both viruses. However, the sequence similar to the GTP-binding motif was not present in the polypeptide encoded by genome segment 4 of WTV.