水稻黄矮病毒基因2的核苷酸序列

NUCLEOTIDE SEQUENCE OF THE RICE YELLOW STUNT RHABDOVIRUS GENE 2

从水稻黄矮病毒（ＲＹＳＶ）基因组的ｃＤＮＡ文库中，获得了包含邻接核衣壳蛋白基因的基因２的克隆，并测定了其核苷酸序列。ＲＹＳＶ基因２的５′端起始序列推测为５′－ＡＡＣＡＣ－３′，该起始序列与ＲＹＳＶ其他基因及其他弹状病毒基因的５′端起始序列高度同源。通过测定感病水稻体内ＲＹＳＶ基因２的转录物的３′端序列，精确地定位了ＲＹＳＶ基因２的３′端终止位点。由此确定ＲＹＳＶ基因２全长１２１１个核苷酸，它含有４２个核苷酸的５′端非翻译区，９６９个核苷酸的蛋白质编码区（包括一个终止密码子）及２００个核苷酸的３′端非翻译区。ＲＹＳＶ基因２编码的蛋白质的氨基酸序列与其它弹状病毒基因２编码的磷酸化蛋白（ＶＳＶ的Ｐ蛋白，ＲＶ的Ｍ１蛋白和ＳＹＮＶ的Ｍ２蛋白）相比，缺乏广泛的同源性，但尚存在一个长约３０个氨基酸的序列保守区域。而且ＲＹＳＶ基因２编码的蛋白中含有７个可被ＣａｓｅｉｎｋｉｎａｓｅⅡ磷酸化的位点（Ｓ／Ｔ－Ｘ－Ｘ－Ｄ／Ｅ），有可能它也是一个磷酸化蛋白。因此推测ＲＹＳＶ基因２编码ＲＹＳＶＮＳ蛋白。

The nucleotide sequence of the gene adjacent to the nucleocapsid protein gene on the rice yellow stunt virus (RYSV) genome,tentatively named gene 2,has been determined from cDNA clones isolated from a RYSV genomic cDNA library.The 5′ end sequence of the gene 2 was putatively assigned as 5′-AACAC-3′, based on homologies to the 5′ end sequences of other RYSV genes and the consensus transcription initiation sequences of other rhabdoviruses.The 3′ end of the gene 2 was defined by sequence analysis of the cDNA corresponding to the 3′ region of the gene 2 transcripts existed in RYSV-infected rice plants.lt was thus concluded that the RYSV gene 2 was 1211 nucleotides (nt) long,comprising a 42nt untranslated 5′region followed by a 969nt open reading frame(including the termination codon)and a 200nt untranslated 3′ sequence.Comparison of the deduced amino acid sequence of the RYSV gene 2-encoded protein with those of VSV P protein,RV M1 protein and SYNV M 2 pro￣tein,which all encoded by genes at the same location in the respective viral genomes,revealed no extensive sequence homologies.Nevertheless,a peptied stretch of about 30 amino acids displaying significant sequence similarity with the above mentionde rhabdovirus proteins could be iden￣tified.Moreover the RYSV gene 2 encoded protein contained seven potential Casein kinase Ⅱ phosphorylation sites (S/T-X-X-D/E),suggesting it might be also a phosphoprotein.We then postulate that the RYSV gene 2 might encode the NS protein.