| Archaeal viruses represent one of the most mysterious parts of the virus kingdom,and their particularity can be extended from rich morphological features to the genome sequence and protein structure encoded by genes,The very small number of homologous proteins is sufficient to prove that it is different from bacterial viruses and eukaryotic viruses.The study of the structure of archaeal viruses is of great significance for exploring the interaction,origin and evolutionary relationship between viruses and their hosts in the unknown world.Compared with the study of bacteriophage structure,the study of archaeal virus structure is still in its infancy.The structure of the spindle virus is the most reported among archaeal viruses.Due to its large molecular weight and unusual characteristics during life,it has brought great challenges to the existing structural research methods.At present,the resolution of the spindle-shaped virus structure obtained by cryo-electron microscopy is generally very low,and only the morphological characteristics of the virus structure can be seen.The low-resolution structural features cannot make accurate inferences about the mechanism of infection,assembly,and genome release in the virus life cycle.Sulfolobus spindle-shaped viruses 19 is a member of the archaeal spindle-shaped viruses,the virus SSV19 is currently researched only at the stage of biochemical experiments,and the study of its structure has not been reported yet.This article takes the spindle virus SSV19 as the research object.Using the RELION software package and our self-developed biomacromolecule symmetry mismatch reconstruction and local reconstruction methods to analyze the overall structure and local structure of the archaeal spindle virus SSV19,the overall structure of the virus with medium resolution and the local virus structure with near-atomic resolution of 3.8 (?) were analyzed.This topic mainly includes the following parts:(1)A new method of near-atom resolution structure analysis of spindle virus based on RELION software package and partial threedimensional reconstruction has been developed.First,multi-conformation virus particles are classified and reconstructed,and then local structure of the virus is boxed based on different types of three-dimensional structures and orientation files,using the method of combining single-particle structure analysis to further reconstruct the local high-resolution structure.This method is universal for the analysis of spindle virus and other lowsymmetric or asymmetrical virus structures.(2)The RELION software package was used to classify SSV19 virus particles in two-dimension structures and three-dimensional structure,through continuous iteration and refinement of the orientation and center of the virus particles,the three-dimensional structure of SSV19 in four states with a resolution of about 9(?) is finally reconstructed,including the complete structure of the tail and capsid.For the first time,a 7-fold symmetry virus assembly pattern and a novel structure different from bacteriophages were discovered.(3)The local symmetry reconstruction method developed by us was used to further reconstruct the three-dimensional structure of SSV19 tail and capsid protein of about 3.8 (?).The atomic structure models of capsid protein VP1,tail proteins c131,b210 and VP4 were constructed, and the structure of each protein and the interaction between the proteins were analyzed.Based on the atomic structure model,the biological functions and possible molecular mechanisms of each protein are discussed,which provides more structural information for understanding the life cycle of archaeal viruses. |
PDF Full Text Request