Xiao Zuoxiang, Xiong Yong, Zhang Wenyan, Tan Lindi, Ehrlich Elana, Guo Deyin, Yu Xiao-Fang
Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
J Mol Biol. 2007 Oct 26;373(3):541-50. doi: 10.1016/j.jmb.2007.07.029. Epub 2007 Jul 26.
Human immunodeficiency virus tyoe 1 (HIV-1) Vif counteracts host restriction cytidine deaminase (APOBEC3G) A3G by co-opting the cellular ubiquitin-proteasome machinery. Vif utilizes a viral-specific BC-box to recruit ElonginB-ElonginC and a novel zinc-binding HCCH motif to recruit Cullin5 (Cul5) to form an E3 ubiquitin ligase targeting A3G for polyubiquitination and subsequently proteasomal degradation. To determine the structural requirements in HIV-1 Vif HCCH motif for Cul5 binding and Vif function, we investigated the arrangement of the His and Cys residues, the role of the spacing between them, and the requirement for the conserved residues. Our data demonstrate that exchanging Cys for His and vice versa in the highly conserved Zn-coordinating HCCH motif disrupted Vif function and interaction with Cul5. Moreover, the maintenance of both conserved residues and spacing within the HCCH motif is critical for Vif function. We have identified a "viral Cul5 box" with consensus Hx2YFxCFx4Phix2APhix7-8Cx5H that is required for Cul5 selection and subsequent A3G degradation. This novel motif may represent a potential new target for anti-viral drug development.
人类免疫缺陷病毒1型（HIV-1）的病毒感染因子（Vif）通过借助细胞内的泛素-蛋白酶体机制来对抗宿主限制胞苷脱氨酶（载脂蛋白B mRNA编辑酶催化多肽样3G，APOBEC3G）A3G。Vif利用病毒特异性的BC盒招募延伸因子B-延伸因子C，并利用一种新型的锌结合HCCH基序招募Cullin5（Cul5），以形成一种E3泛素连接酶，将A3G靶向多聚泛素化，随后进行蛋白酶体降解。为了确定HIV-1 Vif HCCH基序中与Cul5结合及Vif功能相关的结构要求，我们研究了组氨酸（His）和半胱氨酸（Cys）残基的排列方式、它们之间间隔的作用以及对保守残基的需求。我们的数据表明，在高度保守的锌配位HCCH基序中，将Cys与His互换会破坏Vif功能以及与Cul5的相互作用。此外，HCCH基序内保守残基和间隔的维持对于Vif功能至关重要。我们鉴定出了一个“病毒Cul5盒”，其共有序列为Hx2YFxCFx4Phix2APhix7 - 8Cx5H，这是选择Cul5及随后降解A3G所必需的。这个新基序可能代表了抗病毒药物开发的一个潜在新靶点。
