中文摘要：

马铃薯Y病毒属病毒编码的辅助成分-蛋白酶（helper component-proteinase,HC-Pro）是第一个被鉴定的RNA沉默抑制因子。本研究通过定点突变的方法获得了马铃薯A病毒（Potato virus A,PVA）HC-Pro的3个突变体,利用农杆菌共浸润的方法分析了这些突变对HC-Pro抑制RNA沉默活性的影响。与野生型HC-Pro处理相比,Phe6、Asn11缺失突变体的处理中绿色荧光减弱,而Ile250-Gly251-Asn252（IGN）基序中的Ile和Gly分别突变为Asp和Glu的处理中观察不到绿色荧光。该结果表明Phe6、Asn11和IGN2503个位点均参与调控HC-Pro的抑制RNA沉默活性。

英文摘要：

The helper component-proteinase （HC-Pro） encoded by potyviruses is the first identified RNA silencing suppressor. In the study, three mutants of Potato virus A （PVA） HC-Pro were obtained via site-directed mutagenesis and analyzed for their activities on RNA silencing via agroinfiltration. Compared with that of wild type HC-Pro, the treatment with deletion mutants of amino acids Phe6 and Asnn resulted in reduced green fluorescence, while treatment with substitution mutant of Ile250-Gly251-Asn252 motif to Asp250Glu251Asn252 resulted in no fluorescence. These results suggested that amino acids Phe6, Asnll and motif Ile250-Gly251-Asn252 are involved in modulating the RNA silencing suppression activity of HC-Pro.