PAC:PB1N復(fù)合體的三維結(jié)構(gòu),。其中“龍嘴”部位的紫色飄帶為PB1 N端多肽,，“龍頭”為PA_C亞基,； 背景為禽流感病毒的電鏡負(fù)染圖片及病毒顆粒剖面示意圖。
近年來,，由H5N1亞型禽流感病毒引起的疫情廣泛傳播對人類的健康造成全球性的重大威脅,。由于病毒的不斷變異，開發(fā)新型抗流感藥物成為各國極為迫切的重大課題,。其中,，揭示與流感病毒密切相關(guān)的蛋白質(zhì)的三維結(jié)構(gòu)不僅對揭示流感病毒復(fù)制機(jī)制具有重要科學(xué)意義，而且對開發(fā)抗流感病毒藥物具有重要價值,。最近,，由中科院生物物理研究所劉迎芳研究員領(lǐng)導(dǎo)的研究組和饒子和院士領(lǐng)導(dǎo)的研究小組在這一領(lǐng)域取得突破性進(jìn)展，他們在國際上率先揭示了流感病毒聚合酶關(guān)鍵部分PA亞基與PB1多肽復(fù)合體的精細(xì)三維結(jié)構(gòu),。
流感A病毒聚合酶由三種蛋白組成——PA,、PB1和PB2，是轉(zhuǎn)錄和復(fù)制的關(guān)鍵?，F(xiàn)在,，兩個小組報(bào)告了禽流感病毒H5N1 PA 的C-端區(qū)域在與PB1的PA結(jié)合區(qū)域所形成的復(fù)合物中的晶體結(jié)構(gòu)。這項(xiàng)結(jié)構(gòu)研究對于新型抗病毒藥物的設(shè)計(jì)可能會有用
流感病毒基因組含有8個RNA片段,，已知可以編碼11種病毒蛋白質(zhì),。其中，由PA,PB1和PB23個亞基組成的聚合酶復(fù)合體是負(fù)責(zé)病毒基因組RNA復(fù)制以及病毒mRNA轉(zhuǎn)錄的關(guān)鍵組分,，同時由于它的高度保守性,、低突變率，成為抗流感病毒藥物設(shè)計(jì)的重要靶點(diǎn),。多年來的研究認(rèn)為,，PB1是病毒RNA聚合酶的催化亞基，負(fù)責(zé)病毒RNA的復(fù)制以及轉(zhuǎn)錄,；PB2是負(fù)責(zé)以一種稱為“Snatch”的方式奪取宿主mRNA的CAP帽子結(jié)構(gòu)用于病毒mRNA轉(zhuǎn)錄,。而PA亞基不但參與病毒復(fù)制過程,，而且還參與病毒RNA轉(zhuǎn)錄,、內(nèi)切核酸酶活性、具有蛋白酶活性以及參與病毒粒子組裝等多種病毒活動過程,，因而在整個聚合酶復(fù)合體的研究中顯得格外重要,。在經(jīng)過晶體生長條件篩選、晶體質(zhì)量優(yōu)化,、高分辨率數(shù)據(jù)收集,、相位解析、電子密度圖解釋以及結(jié)構(gòu)修正等難關(guān),，他們利用全新的思路,，解析了PA與PB1氨基端多肽蛋白復(fù)合體的2.9埃分辨率晶體結(jié)構(gòu),。該結(jié)構(gòu)清晰顯示了PA與PB1多肽相互作用模式，發(fā)現(xiàn)該作用位點(diǎn)的氨基酸殘基在流感病毒中高度保守,，這為廣譜抗流感(包括人流感和禽流感)藥物研究提供了一個理想的靶蛋白,。同時，根據(jù)該復(fù)合體結(jié)構(gòu)以及已知的一些蛋白突變體研究結(jié)果,，推測了PA亞基在聚合酶中作用,，為進(jìn)一步功能研究提供了分子基礎(chǔ)。這一復(fù)合體結(jié)構(gòu)的揭示,，對揭示流感病毒聚合酶作用機(jī)制以及開展針對流感病毒藥物設(shè)計(jì)工作都具有十分重要意義,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 454, 1123-1126 (28 August 2008) | doi:10.1038/nature07120
Crystal structure of the polymerase PAC–PB1N complex from an avian influenza H5N1 virus
Xiaojing He1, Jie Zhou1, Mark Bartlam2, Rongguang Zhang3, Jianyuan Ma1, Zhiyong Lou4, Xuemei Li1,4, Jingjing Li1, Andrzej Joachimiak3, Zonghao Zeng1, Ruowen Ge5, Zihe Rao1,2,4 & Yingfang Liu1
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
College of Life Sciences and Tianjin State Laboratory of Protein Sciences, Nankai University, Tianjin 300071, China
Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
Laboratory of Structural Biology, Tsinghua University, Beijing 100084, China
Department of Biological Sciences, National University of Singapore, 117543 Singapore
Correspondence to: Zihe Rao1,2,4Yingfang Liu1 Correspondence and requests for materials should be addressed to Z.R. (Email: [email protected]) or Y.L. (Email: [email protected]).
The recent emergence of highly pathogenic avian influenza A virus strains with subtype H5N1 pose a global threat to human health1. Elucidation of the underlying mechanisms of viral replication is critical for development of anti-influenza virus drugs2. The influenza RNA-dependent RNA polymerase (RdRp) heterotrimer has crucial roles in viral RNA replication and transcription. It contains three proteins: PA, PB1 and PB2. PB1 harbours polymerase and endonuclease activities and PB2 is responsible for cap binding3, 4; PA is implicated in RNA replication5, 6, 7, 8, 9, 10 and proteolytic activity11, 12, 13, 14, although its function is less clearly defined. Here we report the 2.9 ångström structure of avian H5N1 influenza A virus PA (PAC, residues 257–716) in complex with the PA-binding region of PB1 (PB1N, residues 1–25). PAC has a fold resembling a dragon's head with PB1N clamped into its open 'jaws'. PB1N is a known inhibitor that blocks assembly of the polymerase heterotrimer and abolishes viral replication. Our structure provides details for the binding of PB1N to PAC at the atomic level, demonstrating a potential target for novel anti-influenza therapeutics. We also discuss a potential nucleotide binding site and the roles of some known residues involved in polymerase activity. Furthermore, to explore the role of PA in viral replication and transcription, we propose a model for the influenza RdRp heterotrimer by comparing PAC with the 3 reovirus polymerase structure, and docking the PAC structure into an available low resolution electron microscopy map.
