Effects of mutations in the beet western yellows virus readthrough protein on its expression and packaging and on virus accumulation, symptoms, and aphid transmission
Effects of mutations in the beet western yellows virus readthrough protein on its expression and packaging and on virus accumulation, symptoms, and aphid transmission
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DOI：
10.1006/viro.1997.8476
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发表时间：
1997-04-14
期刊：
影响因子：
3.7
通讯作者：
Herrbach, E
中科院分区：
文献类型：
--
作者：
Bruyere, A;Brault, V;Herrbach, E
甜菜西方黄化黄症病毒的病毒粒子包含一种主要衣壳蛋白（P22.5）和一种次要通读蛋白（P74），后者是通过主要衣壳蛋白序列向相邻开放阅读框的翻译通读产生的，该相邻开放阅读框编码通读结构域（RTD）。RTD包含病毒在农杆菌侵染的植物中高效积累以及蚜虫传播所必需的决定簇。在黄症病毒中，RTD的C末端部分保守性不强，但N末端部分包含许多保守的序列基序，包括一个富含脯氨酸的序列，它将RTD的其余部分与对应主要外壳蛋白的序列分隔开来。为了将不同的生物学功能定位到这些区域，在RTD的不同位点引入了短的框内缺失，并且将突变基因组作为转录本传递到原生质体中，并通过农杆菌侵染传递到克利夫兰烟中。RTD非保守部分的缺失并不阻碍蚜虫传播，但对植物中病毒的积累有适度的抑制作用，并消除了症状。脯氨酸序列以及保守区和非保守区之间连接部分的缺失使原生质体中通读蛋白的积累抑制了至少10倍。这些突变体在植物中积累少量病毒，不诱导症状，并且使用农杆菌侵染的植物、感染原生质体的提取物或纯化病毒作为接种源时不能被蚜虫传播。RTD保守部分的其他缺失没有显著减少通读蛋白的积累，但阻止了其掺入病毒粒子中。这些突变体在农杆菌侵染的植物中积累到较低水平并引发症状，但不能被蚜虫传播。已经绘制了一个初步图谱，将这些功能定位到RTD的不同部分。（C）1997学术出版社
Virions of beet western yellows luteovirus contain a major capsid protein (P22.5) and a minor readthrough protein (P74), produced by translational readthrough of the major capsid protein sequence into the neighboring open reading frame, which encodes the readthrough domain (RTD). The RTD contains determinants required for efficient virus accumulation in agroinfected plants and for aphid transmission. The C-terminal halves of the RTD are not well conserved among luteoviruses but the N-terminal halves contain many conserved sequence motifs, including a proline-rich sequence separating the rest of the RTD from the sequence corresponding to the major coat protein. To map different biological functions to these regions, short in-frame deletions were introduced at different sites in the RTD and the mutant genomes were transmitted to protoplasts as transcripts and to Nicotiana clevelandii by agroinfection. Deletions in the nonconserved portion of the RTD did not block aphid transmission but had a moderate inhibitory effect on virus accumulation in plants and abolished symptoms. Deletion of the proline tract and the junction between the conserved and nonconserved regions inhibited readthrough protein accumulation in protoplasts by at least 10-fold. The mutants accumulated small amounts of virus in plants, did not induce symptoms, and were nontransmissible by aphids using agroinfected plants, extracts of infected protoplasts, or purified virus as a source of inoculum. Other deletions in the conserved portion of the RTD did not markedly diminish readthrough protein accumulation but abolished its incorporation into virions. These mutants accumulated to low levels in agroinfected plants and elicited symptoms, but could not be aphid-transmitted. A preliminary map has been produced mapping these functions to different parts of the RTD. (C) 1997 Academic Press.