Structural and functional studies of the abundant tegument protein ORF52 from murine gammaherpesvirus 68
Structural and functional studies of the abundant tegument protein ORF52 from murine gammaherpesvirus 68
复制标题
DOI：
10.1074/jbc.m705637200
复制
发表时间：
2007-10-26
影响因子：
4.8
通讯作者：
Tong, Liang
中科院分区：
文献类型：
--
作者：
Benach, Jordi;Wang, Lili;Tong, Liang
被皮是疱疹病毒的核衣壳和包膜之间的一层蛋白质。大多数被膜蛋白的功能仍然知之甚少。在鼠γ疱疹病毒68中，ORF52是一种丰富的被膜蛋白，具有135个残基，是感染性病毒颗粒组装和释放所必需的。为了帮助理解这种蛋白质功能的分子基础，我们以2.1埃的分辨率确定了它的晶体结构。结构揭示了这种蛋白质的二聚体结合。有趣的是，在二聚体的两个单体中，具有不同构象的n端α -螺旋介导了不对称四聚体的形成，并包含许多高度保守的残基。结构和序列分析表明，这种螺旋结构更有可能与病毒的被膜或核衣壳的其他成分相互作用，ORF52的功能是对称二聚体。ORF52的不对称四聚体可能是该蛋白的“潜伏”形式，当它不参与病毒粒子组装时。通过共免疫沉淀和荧光共振能量转移实验证实了ORF52的自缔合性。n端α -螺旋的缺失，以及保守的Arg（95）残基的突变，使ORF52的功能消失。功能研究结果与结构观察结果完全一致，表明n端α -螺旋是ORF52的关键相互作用位点。
The tegument is a layer of proteins between the nucleocapsid and the envelope of herpesviruses. The functions of most tegument proteins are still poorly understood. In murine gammaherpesvirus 68, ORF52 is an abundant tegument protein of 135 residues that is required for the assembly and release of infectious virus particles. To help understand the molecular basis for the function of this protein, we have determined its crystal structure at 2.1 angstrom resolution. The structure reveals a dimeric association of this protein. Interestingly, an N-terminal alpha-helix that assumes different conformation in the two monomers of the dimer mediates the formation of an asymmetrical tetramer and contains many highly conserved residues. Structural and sequence analyses suggest that this helix is more likely involved in interactions with other components of the tegument or nucleocapsid of the virus and that ORF52 functions as a symmetrical dimer. The asymmetrical tetramer of ORF52 may be a "latent" form of the protein, when it is not involved in virion assembly. The self-association of ORF52 has been confirmed by co-immunoprecipitation and fluorescence resonance energy transfer experiments. Deletion of the N-terminal alpha-helix, as well as mutation of the conserved Arg(95) residue, abolished the function of ORF52. The results of the functional studies are fully consistent with the structural observations and indicate that the N-terminal alpha-helix is a crucial site of interaction for ORF52.