Lecture5 September-29-09 2:05PM (1)Lipids, Carbohydrates,Polyamines--p. 22 { Allthree:notallvirushavethese Carbohydrates { Lasttime Lipids { Lipidsandcarbohydrates:essentialforinfectivity { Somelipidsinteractwithproteins=lipoproteins { Lipidsnotsynthesizedbyvirus:simplytakingapieceofmembraneitself Someviruses(paramyxovirusese.g.measles)containlipidsandglycoproteins-->componentsformviralenvelopes(Glycoproteinsformthe spikes,whichprojectfromthevirusparticle.) Envelopedviruseshavelipids-->lipidsaresolubletoorganicsolvents(i.e.Oil,alcohol),therefore,ifwashhandswith70%alcohol,destroy viruseswithenvelopes Ifdestroyenvelopes:virusdead-->glycoproteinsonenvelopeishowvirusattachestothecell BUTsomeviruses(HepatitsA):noenvelopes-->alcoholdoesntaffectthem { Lipidcontainingviruses:usuallyreleasedfrominfectedcellsbyabuddingprocess Similaritiesbetweencellmembraneandviralenvelope-->Viralmembranemostlyoriginatefromcellmembrane Virallipidssameascelllipids:cholesterol,phospholipids(sphingomyelin,phosphatidylcholine,phosphatidylserine,etc)-->foundin CERTAINviruses(enveloped) Buddingprocess:onceyouputsugaron protein-->=puttingzipcodeon letter,straighttomembraneofthecell Cellshavemachinerythatputsugaronprotein,virusknowsglycosylationsignal Virusesthatdonthaveenvelope:dontbud,butlysecellandkillsit--->thosethatdo:budoutand takeapieceofmembranewithit { Viralproteinsinteractwithvirallipids:bondsarehydrophobic&H-bonds(nocovalent) { Mostare involvedintheinfectivityprocess:glycoproteinsonmembrane-->spikesonenvelope-->destroythis,destroyglycoprotein--> thuslipidscontributetostabilityofviralenvelopes { Howdoesavirusanchoritselfintothemembraneofthecell? Proteinhasinthemiddleofthem:alotofLeucine-->hydrophobicaminoacid-->Leucinecomesincontactwithmembrane(lipidbilayer) Ontheoutermembraneofthecell:cellhasHAand NA Viruscomesthroughthecell,bud,tak
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