Beetham P R, Hafner G J, Harding R M, Dale J L
Centre for Molecular Biotechnology, School of Life Science, Queensland University of Technology, Brisbane, Australia.
J Gen Virol. 1997 Jan;78 ( Pt 1):229-36. doi: 10.1099/0022-1317-78-1-229.
We have mapped the mRNA transcripts of banana bunchy top virus (BBTV) DNA-1. Northern hybridization and 3' RACE analysis identified two poly-adenylated RNAs associated with BBTV DNA-1. Previously, one major ORF in the virion sense of DNA-1 had been identified, which encoded a putative replication protein (Rep). An mRNA was identified in BBTV infected bananas that was clearly transcribed from this Rep ORF. Further, a second transcript was identified which mapped to an ORF completely within the Rep ORF. This encoded a putative 5 kDa protein of unknown function. Both these transcripts were also identified in a tobacco plant that had been transformed with Agrobacterium tumefaciens harbouring a binary construct containing the Rep ORF from BBTV DNA-1. This Rep ORF was inserted 3' of a cauliflower mosaic virus 35S promoter and 5' of a vegetable storage protein terminator. The transcripts mapped from these tobacco plants were identical at the 3' end to the transcripts from BBTV infected banana plants. The site of polyadenylation for the Rep ORF was at base 963 immediately 3' of the translational stop codon confirming that the polyadenylation signals for this transcript were all within the ORF. However, the internal ORF had a large untranslated region of 272 bases with its site of polyadenylation at nucleotide 803 and a polyadenylation signal 3' of the translational stop codon. A possible upstream termination signal (A/TTGTAA) was identified and was conserved within BBTV DNA-1 sequences from different international isolates.
我们已绘制了香蕉束顶病毒（BBTV）DNA - 1的mRNA转录本图谱。Northern杂交和3' RACE分析确定了与BBTV DNA - 1相关的两种多聚腺苷酸化RNA。此前，已在DNA - 1的病毒链中鉴定出一个主要开放阅读框（ORF），其编码一种假定的复制蛋白（Rep）。在受BBTV感染的香蕉中鉴定出一种mRNA，它显然是从这个Rep ORF转录而来的。此外，还鉴定出了第二种转录本，其定位到一个完全位于Rep ORF内的ORF。它编码一种功能未知的假定5 kDa蛋白。在一株用含有来自BBTV DNA - 1的Rep ORF的二元构建体的根癌农杆菌转化的烟草植株中也鉴定出了这两种转录本。这个Rep ORF插入到花椰菜花叶病毒35S启动子的3'端和一种蔬菜贮藏蛋白终止子的5'端。这些烟草植株中定位的转录本在3'端与受BBTV感染的香蕉植株的转录本相同。Rep ORF的多聚腺苷酸化位点位于翻译终止密码子3'端紧邻的第963位碱基处，这证实该转录本的多聚腺苷酸化信号都在ORF内。然而，内部ORF有一个272个碱基的大非翻译区，其多聚腺苷酸化位点在核苷酸803处，且多聚腺苷酸化信号在翻译终止密码子的3'端。鉴定出了一个可能的上游终止信号（A/TTGTAA），并且在来自不同国际分离株的BBTV DNA - 1序列中是保守的。
