López-Moya J J, Pirone T P
Department of Plant Pathology, University of Kentucky, Lexington 40546, USA.
J Gen Virol. 1998 Jan;79 ( Pt 1):161-5. doi: 10.1099/0022-1317-79-1-161.
Mutants of tobacco vein mottling virus (TVMV) with substitutions of Lys or Arg for Asp in the DAG motif at position 5 in the coat protein (CP) failed to infect tobacco plants systemically, but replicated and produced virions in protoplasts. Occasional systemic infections occurred when Nicotiana benthamiana or transgenic tobacco plants expressing wild-type TVMV CP were inoculated with these mutants, but viral progeny contained reversions to negatively or non-charged amino acids at position 5 or substitutions of Glu for Lys at position 8. The compensatory nature of these mutations was demonstrated by recreating one of the most common alterations. Tobacco etch virus (TEV) mutants with substitutions of Lys for Asp in the two DAG motifs near the CP N terminus also failed to infect tobacco plants systemically, and in situ histochemical analysis showed limited movement. A certain net charge evidently must be maintained near the CP N terminus for systemic movement to occur.
烟草脉斑驳病毒（TVMV）的外壳蛋白（CP）第5位DAG基序中的天冬氨酸被赖氨酸或精氨酸取代的突变体无法系统感染烟草植株，但能在原生质体中复制并产生病毒粒子。当用这些突变体接种本氏烟草或表达野生型TVMV CP的转基因烟草植株时，偶尔会发生系统感染，但病毒后代在第5位含有回复为负电荷或不带电荷氨基酸的突变，或在第8位含有谷氨酸取代赖氨酸的突变。通过重现其中一种最常见的改变，证明了这些突变的补偿性质。烟草蚀纹病毒（TEV）在CP N端附近的两个DAG基序中天冬氨酸被赖氨酸取代的突变体也无法系统感染烟草植株，原位组织化学分析显示其移动受限。为了发生系统移动，显然必须在CP N端附近维持一定的净电荷。
