病毒的基因组与结构医学课件

1、Viral Genome and StructuresLaboratory of Medical Molecular VirologyChang LiuViral Genome and StructuresLabv.163/special/opencourse/virology.htmlv.163/special/opencourse/virolBreakthrough in 1950sThe viral nucleic acid genome carries the information needed to replicate, build, and spread virions in t

2、he world.One of the building blocks of Molecular BiologyT4, TMVBreakthrough in 1950sThe viraHershey-Chose experimentwith phage T4Fraenkel-Conrats work with TMVHershey-Chose experimentFraenkSeven Genome TypesEither DNA or RNAStructurally diverse: linear, circular, segmented, gapped, single-stranded (

3、+) strand, single-stranded (-) strand, single stranded (ambisense), double-stranded, some have covalently attached proteins, some have cross-linked ends of double-stranded DNARNA World hypothesisSeven Genome TypesEither DNA o病毒的基因组与结构医学课件What information is encoded in a viral genome？Replication of v

4、iral genomeAssembly and packaging of the genomeRegulation and timing of the replication cycleModulation of host defensesSpread to other cells and hostsWhat information is encoded inInformation Not contained in viral genomesNo genes encoding the complete protein synthesis machineryNo genes encoding p

5、rotein involved in energy production or membrane biosynthesisNo classical centromeres or telomeres found in standard host chromosomesInformation Not contained in vThe Baltimore SystemViral genome must make mRNA that can be read by host ribosomesThe Baltimore SystemViral genoNOT all(+) RNA is mRNAEac

6、h way has unique polymerase, primer, template and termination requirementsEach virus family has its own characteristic genome strategyNOT all(+) RNA is mRNASeven classes distinguished by genome replication strategiesds DNA, ss DNASeven classes distinguished byds RNA, +ss RNA, -ssRNA, Retrods RNA, +s

7、s RNA, -ssRNA, RetrodsDNA genomesThe problem of replicating the ends of linear DNA molecules through the use of RNA primers.dsDNA genomesThe problem of reCircular ds DNA genomes that are replicated in the nucleusCircular ds DNA genomes that aLinear ds DNA genomes that are replicated in the nucleusLi

8、near ds DNA genomes that are病毒的基因组与结构医学课件Linear ds DNA genomes that are replicated in the nucleusLinear ds DNA genomes that areds DNA genomes that are replicated in the cytoplasmds DNA genomes that are replicssDNA genomesA basic problem with a ssDNA genome:RNA can only be made from a dsDNA template,

9、ssDNA must be converted into dsDNA before mRNA is madeDNA synthesis must precede mRNA productionssDNA genomesA basic problem wLinear ss DNA genomes that are replicated in the nucleusLinear ss DNA genomes that are病毒的基因组与结构医学课件RNA genomes Cells have NO RNA-dependent RNA polymerases (RdRp) to replicate

10、 the genomes of RNA viruses, or to make mRNA from RNARNA virus genomes encode novel RdRpPolymerases produce both RNA genomes and mRNA from RNA templates+ssRNA, -ssRNA, dsRNARNA genomes Cells have NO RNA-+ssRNAHepatitis A virus, foot and mouth disease virus, and rhinoviruses which cause the common co

11、ld. The coronaviruses which includes important veterinary viruses and the SARS virus. Hepatitis C virus. Yellow fever virus.+ssRNAHepatitis A virus, foot Positive-strand RNA viruses that make no subgenomic mRNAsPositive-strand RNA viruses thPositive-strand RNA viruses that make one or more subgenomi

12、c mRNAsPositive-strand RNA viruses th-ssRNARdRpReassortment: Influenza virus-ssRNARdRpNegative-strand RNA viruseNegative-strand RNA viruseAmbisense RNA viruseAmbisense RNA viruseDouble-stranded RNA(dsRNA)Many dsRNA genomes are segmenteddsRNA cannot be translated by ribosomesDouble-stranded RNA(dsRNA

13、)Manyds RNA virusesds RNA virusesRetrovirusHIVHTLVIntegrate into the host DNAHBVRetrovirusHIVRetrovirusesRetrovirusesHepadnavirusesHepadnavirusesStructureNanometer: 10-9 metersAtom: 0.2-0.3 nm diameterAlpha helix in protein: 1 nm diameterDNA: 2 nm diameterRibosome: 20 nm diameterPoliovirus: 30 nmMim

14、ivirus: 750 nmStructureNanometer: 10-9 mete病毒的基因组与结构医学课件病毒的基因组与结构医学课件病毒的基因组与结构医学课件Functions of virion proteinsProtection of the genomeAssembly of a stable, protective protein shellSpecific recognition and packaging of the nucleic acid genomeInteraction with host cell membranes to form the envelopeFu

15、nctions of virion proteinsPrDelivery of the genomeBinding to host cell receptorsTransmission of signals that induce uncoating of the genomeInduction of fusion with host cell membranesInteraction with cell components to direct transport of genome to the appropriate sitDelivery of the genomeOther inte

16、ractions with hostWith cell components to ensure efficient infectious cycleWith cell components for transport to sites of assemblyWith the host immune systemOther interactions with hostVirus particles are not inert structuresVirions are metastable structures: have not attainted minimum free energy c

17、onformationGained only when an unfavorable energy barrier is surmounted, following irreversible conformational changes during attachment and entryViruses are molecular machines that play active role in delivery of genomeVirus particles are not inert To be infectious, the particles must be metastable

18、Must protect the genome (stable)Must come apart quickly on infection (unstable)An infectious virion is a molecular machineHas moving parts and does workTo be infectious, the particleVirion structure and functionStructure (the particles; the virion)Created by symmetrical arrangement of many identical

19、 proteins to provide maximal contact and non-covalent bondingFunction (genome delivery)Made possible because the structure is Not permanently bonded togetherCan be taken apart or loosened on infection to releaseVirion structure and functionSThe tools of viral structural biologyElectron microscopyX-r

20、ay crystallographyCryo-electron microscopyNuclear magnetic resonance spectroscopy (NMR)The tools of viral structural TITLE: Artificial Nano “T4 Bacteriophage”Description: “T4 Bacteriophage” is a virus like the robot in the living body.Artificial nano “T4 Bacteriophage” was fabricated by FIB-CVD on S

21、i surface.Size of the artificial nano “T4 Bacteriophage” is about ten times as large as the real virus.It is made of Diamond-like Carbon. It is likely to begin to walk in the nano space! Magnification: 25,000XInstrument: SII NanoTechnology Inc. / SMI2050MS2Submitted by: Reo Kometani & Shinji Matsui

22、(University of Hyogo)TITLE: Artificial Nano “T4 BacStructure of Reovirus Core Determined Via X-ray CrystallographyStructure of Reovirus Core DetEnveloped viruses and coated vesicles cryo-electron microscopy and tomographyEnveloped viruses and coated vHerpes virus protein (red) docks with human cellu

23、lar protein (white)UK scientists have used solution-state NMR spectroscopy for the first time to develop a 3D picture of a herpes virus protein interacting with a key part of the human cellular machinery. The study improves our understanding of how the virus hijacks human cells and could eventually

24、lead to new targets for drug therapy.Herpes virus protein (red) docPrinciples of building virions: Symmetry is keyWatson and Crick did more than discover DNA structure1956: pointed out that most virus particles were spherical or rod-shaped in the EMKnew particles were made with many copies of few pr

25、oteins (genetic economy)Viral proteins have structural properties that permit regular and repetitive interactions among themPrinciples of building virionsThey provide rules for “self-assembly”Rule 1: Each subunit has “identical” bonding contacts with its neighborsRule 2: These bonding contacts are u

26、sually non-covalentThey provide rules for “self-aMany capsid proteins can self assemble into “virus-like particles” (VLPs)The HBV and HPV vaccines are VLPs made in yeastMany capsid proteins can self Helical symmetryHelical symmetry病毒的基因组与结构医学课件Enveloped virions of RNA viruses with ssRNA genomes with

27、 helical capsidsParamyxoviridae (measles virus)Rhabdoviridae (rabies virus）Orthomyxoviridae (influenza virus)Filoviridae (Ebola virus)Enveloped virions of RNA virusHow can you make a round capsid from proteins with irregular shapes?Clue1: All round capsids have precise numbers of proteins; multiples of 60 are common (60, 180, 240, 960) (T number)Clue 2: Spherical viruses come in many size, but capsid proteins are 20-60 kDa av