Methionine-101 from one strain of H5N1 NS1 protein determines its IFN-antagonizing ability and subcellular distribution pattern  

作　　者：MENG Jin ZHANG ZhenFeng ZHENG ZhenHua LIU Yan WANG HanZhong 

机构地区：[1]State Key Laboratory of Virology,Wuhan Institute of Virology,Chinese Academy of Sciences,Wuhan 430071,China

出　　处：《Science China(Life Sciences)》2012年第11期933-939,共7页中国科学（生命科学英文版）

基　　金：supported by the National Basic Research Program of China (Grant No. 2012CB518904)

摘　　要：Influenza A virus NS1 protein has developed two main IFN-antagonizing mechanisms by inhibiting retinoic-acid-inducible gene I (RIG-I) signal transduction, or by suppressing cellular pre-mRNA processing through binding to cleavage and polyad-enylation specific factor 30 (CPSF30). However, the precise effects of NS1 on suppressing type I IFN induction have not been well characterized. Here we report that compared with PR/8/34 NS1, which is localized partially in the cytoplasm and has strong IFN-antagonizing ability via specifically inhibiting IFN-β promoter activity, H5N1 NS1 has strikingly different characteristics. It mainly accumulates in the nucleus of transfected cells and exerts rather weak IFN-counteracting ability through suppression of the overall gene expression. The M101I mutation of H5N1 NS1, namely H5-M101I, fully reversed its functions. H5-M101I gained the ability to specifically inhibit IFN-β promoter activity, translocate to the cytoplasm, and release CPSF30. The previously reported NES (nuclear export signal) (residues 138 147) was unable to lead H5N1 NS1 to translocate. This suggests that other residues may serve as a potent NES. Findings indicated that together with leucine-100, methionine-101 en- hanced the regional NES. In addition, methionine-101 was the key residue for the NS1-CPSF30 interaction. This study reveals the importance of methionine-101 in the influenza A virus life cycle and may provide valuable information for antiviral strategies.Influenza A virus NS1 protein has developed two main IFN-antagonizing mechanisms by inhibiting retinoic-acid-inducible gene I （RIG-I） signal transduction, or by suppressing cellular pre-mRNA processing through binding to cleavage and polyad-enylation specific factor 30 （CPSF30）. However, the precise effects of NS1 on suppressing type I IFN induction have not been well characterized. Here we report that compared with PR/8/34 NS1, which is localized partially in the cytoplasm and has strong IFN-antagonizing ability via specifically inhibiting IFN-β promoter activity, H5N1 NS1 has strikingly different characteristics. It mainly accumulates in the nucleus of transfected cells and exerts rather weak IFN-counteracting ability through suppression of the overall gene expression. The M101I mutation of H5N1 NS1, namely H5-M101I, fully reversed its functions. H5-M101I gained the ability to specifically inhibit IFN-β promoter activity, translocate to the cytoplasm, and release CPSF30. The previously reported NES （nuclear export signal） （residues 138 147） was unable to lead H5N1 NS1 to translocate. This suggests that other residues may serve as a potent NES. Findings indicated that together with leucine-100, methionine-101 en- hanced the regional NES. In addition, methionine-101 was the key residue for the NS1-CPSF30 interaction. This study reveals the importance of methionine-101 in the influenza A virus life cycle and may provide valuable information for antiviral strategies.

关 键 词：influenza A virus H5N1 IFN-Β CPSF30 NES 

分 类 号：S852.659.5[农业科学—基础兽医学] S855.3[农业科学—兽医学]