RNA silencing is a potent antiviral mechanism in plants and animals. As a counter-defense, many viruses studied to date encode one or more viral suppressors of RNA silencing(VSR). In the latter case, how different VSR...RNA silencing is a potent antiviral mechanism in plants and animals. As a counter-defense, many viruses studied to date encode one or more viral suppressors of RNA silencing(VSR). In the latter case, how different VSRs encoded by a virus function in silencing remains to be fully understood. We previously showed that the nonstructural protein Pns10 of a Phytoreovirus, Rice dwarf virus(RDV), functions as a VSR. Here we present evidence that another nonstructural protein, Pns11, also functions as a VSR. While Pns10 was localized in the cytoplasm, Pns11 was localized both in the nucleus and chloroplasts. Pns11 has two bipartite nuclear localization signals(NLSs), which were required for nuclear as well as chloroplastic localization. The NLSs were also required for the silencing activities of Pns11. This is the first report that multiple VSRs encoded by a virus are localized in different subcellular compartments, and that a viral protein can be targeted to both the nucleus and chloroplast. These findings may have broad significance in studying the subcellular targeting of VSRs and other viral proteins in viral-host interactions.展开更多
The Phytoreovirus rice dwarf virus (RDV) has a complex nucleocapsid architecture composed of multiple proteins and RNAs. However, specific RNA-protein and protein-protein interactions involved in virion packaging have...The Phytoreovirus rice dwarf virus (RDV) has a complex nucleocapsid architecture composed of multiple proteins and RNAs. However, specific RNA-protein and protein-protein interactions involved in virion packaging have not been entirely elucidated. In order to define mechanisms governing RDV particle assembly, interactions between individual components were analyzed both in vivo and in vitro. The P7 core protein binds specifically and with high affinity to all 12 genomic RDV dsRNAs. P1, a putative RNA polymerase, P5, a putative guanyltransferase and P7 are encapsidated within the virion and also bind viral transcripts based upon in vitro binding assays. P1, P5, P7 and genomic dsRNAs were lacking in empty particles purified from infected tissues that also yielded fractions containing intact, infectious particles. In addition, P7 forms complexes with P1 and P3, a core capsid protein, in viral particles. These results indicate the possibility that core proteins and dsRNAs interact as one unit suggesting a mechanism for assortment of viral RNAs and subsequent packaging into core particles.展开更多
Rice gall dwarf virus(RGDV)is an important rice pathogen in China and Southeast Asia.However,little is known about the molecular mechanisms of RGDV interactions with plant cells.Here,we have identi-fied an RGDV protei...Rice gall dwarf virus(RGDV)is an important rice pathogen in China and Southeast Asia.However,little is known about the molecular mechanisms of RGDV interactions with plant cells.Here,we have identi-fied an RGDV protein,Pns11,which acts as a suppressor of RNA silencing in coinfiltration assays with the reporter,green fluorescent protein(GFP)in transgenic Nicotiana benthamiana line 16c carrying GFP.Pns11 suppressed local and systemic silencing induced by sense RNA.The spread of mobile RNA si-lencing signals was blocked or inactivated by Pns11.Expression of Pns11 also enhanced Potato virus X pathogenicity in N.benthamiana.This suppressor could reduce,but not eliminate,siRNA in the local and systemic RNA silencing suppression assays,suggesting that Pns11 functions by interfering with initial stages of RNA silencing.展开更多
以采自广东省水稻瘤矮病的典型病株为材料,通过RT-PCR法扩增和克隆了水稻瘤矮病毒(Rice gall dwarf virus,RGDV)S11组分核苷酸序列全长。序列分析结果表明,RGDV广东分离物S11(登录号EF532326)核苷酸序列全长1168bp,含有一个1068bp的开...以采自广东省水稻瘤矮病的典型病株为材料,通过RT-PCR法扩增和克隆了水稻瘤矮病毒(Rice gall dwarf virus,RGDV)S11组分核苷酸序列全长。序列分析结果表明,RGDV广东分离物S11(登录号EF532326)核苷酸序列全长1168bp,含有一个1068bp的开放阅读框,编码一条355个氨基酸的多肽,推测分子量约40kD,与泰国分离物基因结构基本一致,其核苷酸与氨基酸序列相似性分别为94.3%和98.8%。将广东分离物S11基因克隆至pBV221温敏表达载体上,在大肠杆菌DH5α中实现了高效表达。以诱导蛋白为抗原免疫家兔获得了抗血清。利用ELISA法测定抗血清的效价为1∶4096,Western blot分析结果表明,抗血清能与S11蛋白发生特异血清学反应。这可为进一步研究S11蛋白的结构和功能,揭示其抑制基因沉默的作用机制提供参考。展开更多
为初步探究OsAGO家族在水稻抗病毒通路中的功能,对水稻OsAGO蛋白的基因组结构、系统发育关系、氨基酸序列及水稻瘤矮病毒(rice gall dwarf virus,RGDV)和南方水稻黑条矮缩病毒(southern rice black streaked dwarf virus,SRBSDV)侵染后...为初步探究OsAGO家族在水稻抗病毒通路中的功能,对水稻OsAGO蛋白的基因组结构、系统发育关系、氨基酸序列及水稻瘤矮病毒(rice gall dwarf virus,RGDV)和南方水稻黑条矮缩病毒(southern rice black streaked dwarf virus,SRBSDV)侵染后的转录组数据进行分析,同时采用实时荧光定量PCR(quantitative real-time PCR,qPCR)技术对这2种病毒侵染后OsAGO基因的相对表达量变化进行验证。结果表明,19个水稻OsAGO蛋白的外显子数量、内含子数量及编码区长度存在较大差异,且这19个OsAGO蛋白均匀分布在3个分支中;OsAGO蛋白PAZ结构域中与小RNA结合相关的YF(酪氨酸-苯丙氨酸)基序在OsAGO2、OsAGO3和OsAGO5中变成了YY(酪氨酸-酪氨酸),OsAGO蛋白PIWI结构域中与OsAGO蛋白切割活性相关的DDX(X代表H或D,即天冬氨酸-天冬氨酸-组氨酸/天冬氨酸)基序在OsAGO13中替换为LDH(亮氨酸-天冬氨酸-组氨酸)基序,而在OsAGO17中不包含YF基序且DDX基序替换为HDR(组氨酸-天冬氨酸-精氨酸)基序。RGDV侵染后OsAGO5和OsAGO12基因的转录组分析结果与qPCR结果一致,其中OsAGO5上调表达,OsAGO12下调表达;SRBSDV侵染后OsAGO1a、OsAGO1b、OsAGO1c、OsAGO1d和OsAGO4b基因的转录组分析结果与qPCR结果一致,均上调表达。表明大多数OsAGO均能响应RGDV和SRBSDV的侵染。展开更多
基金supported by grants from CARS-01-06 to X.H.X., Transgenic Research Program (2016ZX08010001)the National Natural Science Foundation of China (31530062)。
文摘RNA silencing is a potent antiviral mechanism in plants and animals. As a counter-defense, many viruses studied to date encode one or more viral suppressors of RNA silencing(VSR). In the latter case, how different VSRs encoded by a virus function in silencing remains to be fully understood. We previously showed that the nonstructural protein Pns10 of a Phytoreovirus, Rice dwarf virus(RDV), functions as a VSR. Here we present evidence that another nonstructural protein, Pns11, also functions as a VSR. While Pns10 was localized in the cytoplasm, Pns11 was localized both in the nucleus and chloroplasts. Pns11 has two bipartite nuclear localization signals(NLSs), which were required for nuclear as well as chloroplastic localization. The NLSs were also required for the silencing activities of Pns11. This is the first report that multiple VSRs encoded by a virus are localized in different subcellular compartments, and that a viral protein can be targeted to both the nucleus and chloroplast. These findings may have broad significance in studying the subcellular targeting of VSRs and other viral proteins in viral-host interactions.
文摘The Phytoreovirus rice dwarf virus (RDV) has a complex nucleocapsid architecture composed of multiple proteins and RNAs. However, specific RNA-protein and protein-protein interactions involved in virion packaging have not been entirely elucidated. In order to define mechanisms governing RDV particle assembly, interactions between individual components were analyzed both in vivo and in vitro. The P7 core protein binds specifically and with high affinity to all 12 genomic RDV dsRNAs. P1, a putative RNA polymerase, P5, a putative guanyltransferase and P7 are encapsidated within the virion and also bind viral transcripts based upon in vitro binding assays. P1, P5, P7 and genomic dsRNAs were lacking in empty particles purified from infected tissues that also yielded fractions containing intact, infectious particles. In addition, P7 forms complexes with P1 and P3, a core capsid protein, in viral particles. These results indicate the possibility that core proteins and dsRNAs interact as one unit suggesting a mechanism for assortment of viral RNAs and subsequent packaging into core particles.
基金the National Natural Science Foundation of China(Grant Nos.30370929 and 30671358)
文摘Rice gall dwarf virus(RGDV)is an important rice pathogen in China and Southeast Asia.However,little is known about the molecular mechanisms of RGDV interactions with plant cells.Here,we have identi-fied an RGDV protein,Pns11,which acts as a suppressor of RNA silencing in coinfiltration assays with the reporter,green fluorescent protein(GFP)in transgenic Nicotiana benthamiana line 16c carrying GFP.Pns11 suppressed local and systemic silencing induced by sense RNA.The spread of mobile RNA si-lencing signals was blocked or inactivated by Pns11.Expression of Pns11 also enhanced Potato virus X pathogenicity in N.benthamiana.This suppressor could reduce,but not eliminate,siRNA in the local and systemic RNA silencing suppression assays,suggesting that Pns11 functions by interfering with initial stages of RNA silencing.
文摘以采自广东省水稻瘤矮病的典型病株为材料,通过RT-PCR法扩增和克隆了水稻瘤矮病毒(Rice gall dwarf virus,RGDV)S11组分核苷酸序列全长。序列分析结果表明,RGDV广东分离物S11(登录号EF532326)核苷酸序列全长1168bp,含有一个1068bp的开放阅读框,编码一条355个氨基酸的多肽,推测分子量约40kD,与泰国分离物基因结构基本一致,其核苷酸与氨基酸序列相似性分别为94.3%和98.8%。将广东分离物S11基因克隆至pBV221温敏表达载体上,在大肠杆菌DH5α中实现了高效表达。以诱导蛋白为抗原免疫家兔获得了抗血清。利用ELISA法测定抗血清的效价为1∶4096,Western blot分析结果表明,抗血清能与S11蛋白发生特异血清学反应。这可为进一步研究S11蛋白的结构和功能,揭示其抑制基因沉默的作用机制提供参考。
