昆虫质型多角体病毒与杆状病毒多角体的结构比较

依据已有的研究结果,分析比较昆虫质型多角体病毒和杆状病毒多角体的结构差异。2种病毒都产生多角体,其中质型多角体病毒多角体的原子结构展现一个错综复杂的三聚体组装,即通过多角体蛋白分子突出的N-端螺旋臂互相连接在一起;杆状病毒和质型多角体病毒的多角体晶体相似,蛋白序列的N-末端也是α-螺旋。由此表明这2种病毒的多角体蛋白及其共同结构基础具有同源性。但一些研究表明质型多角体病毒和杆状病毒的多角体基础分子组织形成不同。尽管这2种病毒多角体含有相近的结构单位及共有对称方式,但是多角体分子在结构上差别较大,在晶体内的组装形式也不同,特别是二硫键和N-端区域的区域交叉使杆状病毒多角体的晶体构造稳定坚固,C-端臂使其结构单位相互连接在一起。有研究表明N-末端螺旋突出臂在杆状病毒和质型多角体病毒中也具有不同的结构功能,但目前并没有结构方面的证据证明这2种病毒多角体具有共同的进化起源。

A Comparison on Polyhedral Structures of Insect Cytoplasmic Polyhedrosis Virus and Baculovirus

Based on existing data,the difference of polyhedral structures of cytoplasmic polyhedrosis virus(CPV) and baculovirus were analyzed and compared.Among the polyhedra formed by these two virus species,the atomic structure of CPV’s polyhedra displayed an intricate packing of trimers,which were interconnected by a projecting N-terminal helical arm of the polyhedrin molecule.Baculovirus and CPV had nearly identical polyhedron crystals,and their polyhedrins’ N-terminals were also predicted to be α-helices.These results suggest homology between the polyhedrin and common structural basis of the two virus species.However,a number of studies showed that the underlying molecular organization is different.Although both polyhedra have nearly identical structural unit and common symmetry,the polyhedral molecules are structurally unrelated and pack differently in the crystals.In particular,disulfide bonds and domain-swapped N-terminal domains stabilize the building blocks of baculovirus polyhedra and the interlocking C-terminal arms join structural units together.Studies showed that the N-terminal projecting helical arms also have different structural roles in both baculovirus and CPV.However,no evidence has been found to support the common evolutionary origin of polyhedra from both virus species.