Stewart Lucy R, Jarugula Sridhar, Zhao Yujing, Qu Feng, Marty DeeMarie
USDA-ARS Corn, Soybean and Wheat Quality Research Unit, Wooster, OH, USA; Department of Plant Pathology, Ohio State University, Wooster, OH, USA.
Department of Plant Pathology, Ohio State University, Wooster, OH, USA.
Virology. 2017 Apr;504:88-95. doi: 10.1016/j.virol.2016.11.017. Epub 2017 Feb 1.
Maize chlorotic dwarf virus (MCDV), a member of the genus Waikavirus, family Secoviridae, has a 11784 nt (+)ssRNA genome that encodes a 389kDa proteolytically processed polyprotein. We show that the N-terminal 78kDa polyprotein (R78) of MCDV acts as a suppressor of RNA silencing in a well-established assay system. We further demonstrate that R78 is cleaved by the viral 3C-like protease into 51 and 27kDa proteins (p51 and p27), and that p51 is responsible for silencing suppressor activity. Silencing suppressor activity of R78 is conserved in three divergent MCDV strains (MCDV-Severe, MCDV-M1, and MCDV-Tennessee), as well as the waikavirus Bellflower vein chlorosis virus, but was not detected for orthologous protein of Rice tungro spherical virus (RTSV-A) or the similarly-positioned protein from the sequivirus Parsnip yellow fleck virus (PYFV). This is the first identification of a virus suppressor of RNA silencing encoded by a waikavirus.
玉米褪绿矮缩病毒（MCDV）是分体病毒科怀卡病毒属的成员，具有一个11784个核苷酸的（+）单链RNA基因组，该基因组编码一个经蛋白水解加工的389 kDa多聚蛋白。我们发现在一个成熟的检测系统中，MCDV的N端78 kDa多聚蛋白（R78）可作为RNA沉默抑制子。我们进一步证明，R78被病毒3C样蛋白酶切割成51 kDa和27 kDa的蛋白（p51和p27），并且p51负责沉默抑制子活性。R78的沉默抑制子活性在三种不同的MCDV株系（严重型MCDV、MCDV-M1和田纳西型MCDV）以及怀卡病毒风铃草叶脉褪绿病毒中保守，但在水稻东格鲁球形病毒（RTSV-A）的直系同源蛋白或芜菁黄花叶病毒属Parsnip yellow fleck virus（PYFV）的类似位置蛋白中未检测到。这是首次鉴定出由怀卡病毒编码的RNA沉默病毒抑制子。
