Biomaterial Database

Projection structure of VP6, the rotavirus inner capsid protein, and comparison with bluetongue VP7. 1997

G G Hsu, and A R Bellamy, and M Yeager

Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.

The rotavirus nucleocapsid protein (VP6) is the major structural protein of inner capsid particles (ICP). VP6 is essential for RNA transcription and binds to a virally encoded glycoprotein receptor (NSP4) involved in the rotavirus assembly pathway. To explore the structure of VP6, two-dimensional (2D) crystals of VP6 were generated and examined by electron microscopy and image processing. Fourier transforms computed from low-dose images of negatively stained 2D VP6 crystals displayed complete data to 13 A resolution for p6 plane group symmetry. To correct for the resolution dependent fall-off of the amplitudes derived from electron microscopic images, the rotavirus VP6 amplitudes were scaled to the bluetongue VP7 amplitudes derived from the atomic model by applying a B factor of -360 A-2. The unit cell (a=b=101(+/-2)A, gamma=120(+/-1) degrees) contains two VP6 trimers, each composed of three roughly circular subunits approximately 30 A in diameter. The trimeric organization of VP6 is similar to the oligomeric structure of VP6 when assembled in T=13l icosahedral inner capsid particles at 25 to 40 A resolution. However, a channel at the center of the trimer is better resolved in our map at 15 A resolution. The projection structure of rotavirus VP6 was compared to the homologous protein (VP7) of bluetongue virus, which is also a member of the family of Reoviridae. Notably, both VP6 and bluetongue VP7 assemble as 260 capsomers on the surface of the inner capsid. To compare VP6 and VP7, a projection map of bluetongue VP7 at 15 A resolution was generated using the atomic model derived by X-ray crystallography. VP6 and VP7 both exhibit a trimeric organization with a central channel, even though the alignment identity between the 45 kDa VP6 and the 38 kDa VP7 primary sequences is only 12%. The ability of VP6 to form well-ordered 2D crystals should enable a higher resolution structure analysis by cryo-electron microscopy that will extend our understanding of the icosahedral ICP structure, clarify the mechanism by which VP6 interacts with the NSP4 receptor, and allow a more detailed comparison of VP6 and VP7.

UI	MeSH Term	Description	Entries
D007091	Image Processing, Computer-Assisted	A technique of inputting two-dimensional or three-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.	Biomedical Image Processing,Computer-Assisted Image Processing,Digital Image Processing,Image Analysis, Computer-Assisted,Image Reconstruction,Medical Image Processing,Analysis, Computer-Assisted Image,Computer-Assisted Image Analysis,Computer Assisted Image Analysis,Computer Assisted Image Processing,Computer-Assisted Image Analyses,Image Analyses, Computer-Assisted,Image Analysis, Computer Assisted,Image Processing, Biomedical,Image Processing, Computer Assisted,Image Processing, Digital,Image Processing, Medical,Image Processings, Medical,Image Reconstructions,Medical Image Processings,Processing, Biomedical Image,Processing, Digital Image,Processing, Medical Image,Processings, Digital Image,Processings, Medical Image,Reconstruction, Image,Reconstructions, Image
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D001820	Bluetongue virus	The type species of ORBIVIRUS causing a serious disease in sheep, especially lambs. It may also infect wild ruminants and other domestic animals.	Ovine Catarrhal Fever Virus,Blue Tongue Virus,Blue Tongue Viruses,Bluetongue Viruses
D002213	Capsid	The outer protein protective shell of a virus, which protects the viral nucleic acid. Capsids are composed of repeating units (capsomers or capsomeres) of CAPSID PROTEINS which when assembled together form either an icosahedral or helical shape.	Procapsid,Prohead,Capsids,Procapsids,Proheads
D003461	Crystallography	The branch of science that deals with the geometric description of crystals and their internal arrangement. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Crystallographies
D005583	Fourier Analysis	Analysis based on the mathematical function first formulated by Jean-Baptiste-Joseph Fourier in 1807. The function, known as the Fourier transform, describes the sinusoidal pattern of any fluctuating pattern in the physical world in terms of its amplitude and its phase. It has broad applications in biomedicine, e.g., analysis of the x-ray crystallography data pivotal in identifying the double helical nature of DNA and in analysis of other molecules, including viruses, and the modified back-projection algorithm universally used in computerized tomography imaging, etc. (From Segen, The Dictionary of Modern Medicine, 1992)	Fourier Series,Fourier Transform,Analysis, Cyclic,Analysis, Fourier,Cyclic Analysis,Analyses, Cyclic,Cyclic Analyses,Series, Fourier,Transform, Fourier
D000956	Antigens, Viral	Substances elaborated by viruses that have antigenic activity.	Viral Antigen,Viral Antigens,Antigen, Viral
D012401	Rotavirus	A genus of REOVIRIDAE, causing acute gastroenteritis in BIRDS and MAMMALS, including humans. Transmission is horizontal and by environmental contamination. Seven species (Rotaviruses A thru G) are recognized.	Neonatal Calf Diarrhea Virus,Rotaviruses
D014758	Viral Core Proteins	Proteins found mainly in icosahedral DNA and RNA viruses. They consist of proteins directly associated with the nucleic acid inside the NUCLEOCAPSID.	Core Proteins, Viral,Major Core Protein,Major Core Proteins, Viral,Adenovirus Core Protein VII,Core Protein V,Core Protein lambda 2,Influenza Virus Core Proteins,Major Core Protein lambda 1,Major Core Protein lambda-1,Major Core Protein sigma 2,Major Core Protein sigma-2,OVP 19,Oncornaviral Protein P19,P30 Core Proteins,Viral Protein P19,Virus Core Proteins,Core Protein, Major,Core Proteins, P30,Core Proteins, Virus,Protein P19, Oncornaviral,Protein P19, Viral,Protein, Major Core,Proteins, P30 Core,Proteins, Viral Core,Proteins, Virus Core
D036022	Capsid Proteins	Proteins that form the CAPSID of VIRUSES.	Procapsid Protein,Procapsid Proteins,Viral Coat Protein,Viral Coat Proteins,Viral V Antigens,Viral V Proteins,Capsid Protein,Viral Outer Coat Protein,Antigens, Viral V,Coat Protein, Viral,V Antigens, Viral,V Proteins, Viral