Introduction to MHC
description
Transcript of Introduction to MHC
Sequence/Structure Variability in the Major Histocompatibility Complex Protein Class I alpha chain.
Errol Archibold, Mark Maloney and Rafael Tosado.BioQuest / SCALE-IT Curriculum Workshop, 2009
Introduction to MHC
MHC I Alpha Chain from Different Species
SIXFRAME Analysis of Human MHC alpha I DNA Sequence >BWB5471 Translated - Frame 1KAVYGLGSPSLGDSPTPQFLFSLSQPM*GPSSWILTTRTQFSLPSGVGFPEKPISVVAVAVLKSARTHRDSDSPQTPRMAVMAPRTLVLLLSGALALTQTWAGSHSMRYFFTSVSRPGRGEPRFIAVGYVDDTQFVRFDSDAASQRMEPRAPWIEQEGPEYWDGETRKVKAHSQTHRVDLGTLRGYYNQSEAGSHTVQRMYGCDVGSDWRFLRGYHQYAYDGKDYIALKEDLRSWTAADMAAQTTKHKWEAAHVAEQLRAYLEGTCVEWLRRYLENGKETLQRTDAPKTHMTHHAVSDHEATLRCWALSFYPAEITLTWQRDGEDQTQDTELVETRPAGDGTFQKWAAVVVPSGQEQRYTCHVQHEGLPKPLTLRWEPSSQPTIPIVGIIAGLVLFGAVITGAVVAAVMWRRKSSDRKGGSYSQAASSDSAQGSDVSLTACKV* >BWB5471 Translated - Frame 2RRCMDWGVPALGIPQLRSFFSPSPNLCRVLLPGYSRRGPSSHSHRVSGFQRSQSVSSRSRF*SPHAPTGTQILPRRRGWPSWRPEPSSCYSRGLWP*PRPGRALTP*GISSHPCPGPAAGSPASSQWATWTTRSSCGSTATPRARGWSRGRRG*SRRVRSIGTGRHGK*RPTHRLTEWTWGPCAATTTRARPVLTPSRGCMAATWGRTGASSAGTTSTPTTARITSP*KRTCALGPRRTWQLRPPSTSGRRPMWRSS*EPTWRARAWSGSADTWRTGRRRCSARTPPKRI*LTTLSLTMKPP*GAGP*ASTLRRSH*PGSGMGRTRPRTRSSWRPGLQGMEPSRSGRLWWCLLDRSRDTPAMCSMRVCPSPSP*DGSRLPSPPSPSWASLLAWFSLEL*SLELWSLL*CGGGRAQIEKEGATLRLQAVTVPRALMCLSQLVKC >BWB5471 Translated - Frame 3GGVWIGESQPWGFPNSAVSFLPLPTYVGSFFLDTHDADPVLTPIGCRVSREANQCRRGRGSKVRTHPPGLRFSPDAEDGRHGAPNPRPATLGGSGPDPDLGGLSLHEVFLHIRVPARPRGAPLHRSGLRGRHAVRAVRQRRREPEDGAAGAVDRAGGSGVLGRGDTESEGPLTDSPSGPGDPARLLQPERGRFSHRPEDVWLRRGVGLALPPRVPPVRLRRQGLHRPERGPALLDRGGHGSSDHQAQVGGGPCGGAVESLPGGHVRGVAPQIPGEREGDAAAHGRPQNAYDSPRCL*P*SHPEVLGPELLPCGDHTDLAAGWGGPDPGHGARGDQACRGWNLPEVGGCGGAFWTGAEIHLPCAA*GFAQAPHPEMGAVFPAHHPHRGHHCWPGSLWSCDHWSCGRCCDVEEEELR*KRRELLSGCKQ*QCPGL*CVSHSL*SV >BWB5471 Translated - Frame 4SHFTSCERHIRALGTVTACSLRVAPSFSI*ALPPPHHSSDHSSSDHSSKENQASNDAHDGDGGLGRRLPSQGEGLGQTLMLHMAGVSLLLSRRHHHSRPLLEGSIPCRPGLHELRVLGLVLPIPLPGQCDLRRVEAQGPAPQGGFMVRDSVVSHMRFGGVRALQRLLPVLQVSAEPLHARALQVGSQLLRHMGRLPLVLGGLSCHVRRGPRAQVLFQGDVILAVVGVLVVPAEEAPVRPHVAAIHPLDGVRTGLALVVVAAQGPQVHSVSL*VGLHFPCLPVPILRTLLLYPRRPRLHPLARGVAVEPHELRVVHVAHCDEAGLPAAGPGHGCEEIPHGVRARPGLGQGQSPRE*QDEGSGRHDGHPRRLGRI*VPVGACGL*NRDRDDTDWLLWKPDTRWE*ELGPRREYPGRRTLHRLGEGEKKLRSWGIPKAGTPQSIHRL >BWB5471 Translated - Frame 5HTLQAVRDTSEPWALSLLAA*E*LPPFLSELFLLHITAATTAPVITAPKRTRPAMMPTMGMVGWEDGSHLRVRGLGKPSCCTWQVYLCSCPEGTTTAAHFWKVPSPAGLVSTSSVSWVWSSPSRCQVSVISAG*KLRAQHLRVASWSETAW*VICVLGASVRCSVSFPFSRYLRSHSTHVPSR*ALNCSATWAASHLCLVV*AAMSAAVQERRSSFRAM*SLPS*AYWWYPRRKRQSDPTSQPYILWTV*EPASLWL**PRRVPRSTR*VCEWAFTFRVSPSQYSGPSCSIHGARGSILWLAASLSNRTNCVSST*PTAMKRGSPRPGRDTDVKKYLME*EPAQVWVRARAPESSRTRVRGAMTAILGVWGESESRWVRADFRTATATTLIGFSGNPTPDGSENWVRVVSIQEEGPYIGWEREKRNCGVGESPRLGLPNPYTA >BWB5471 Translated - Frame 6TLYKL*ETHQSPGHCHCLQPESSSLLFYLSSSSSTSQQRPQLQ*SQLQREPGQQ*CPRWGWWAGKTAPISG*GAWANPHAAHGRCISAPVQKAPPQPPTSGRFHPLQAWSPRAPCPGSGPPHPAARSV*SPQGRSSGPSTSGWLHGQRQRGESYAFWGRPCAAASPSRSPGICGATPRTCPPGRLSTAPPHGPPPTCAWWSELPCPPRSKSAGPLSGRCNPCRRRRTGGTRGGSASPTPRRSHTSSGRCENRPRSGCSSRAGSPGPLGESVSGPSLSVSPRPNTPDPPALSTAPAAPSSGSRRRCRTARTACRPRSPLR*SGAPRGRAGTRM*RNTSWSESPPRSGSGPEPPRVAGRGFGAP*RPSSASGENLSPGGCVRTLEPRPRRH*LASLETRHPMGVRTGSAS*VSRKKDPT*VGRGRKETAELGNPQGWDSPIHTPP
MHC I Alpha Chain Human Variants
MHC I Alpha Chain Structure
http://consurf.tau.ac.il/fgij/fg.htm?mol=/results/1245796831/2guo_consurf1245796831_pipe.pdb
MHC I Alpha Chain Species Tree
Conclusions
•Presentation of antigenic peptides to T cells.•Rejection of transplanted tissues.• Highly polymorphic genes.•Unlike enzymes, variation tends to be in the “active” site
• Class I and II molecules• Class I in all nucleated cells.• Class II in Antigen (Ag) Presenting Cells (APC).
• T-cell receptor (TCR) –Ag complex• CD8 interact with Ag on MHCI• CD4 interact with Ag on MHCII
• Crystal Structure revealed differences and similarities• Antigen-binding groove• Opposing alpha helixes at the opening• Beta chains for the floor of the groove
• MHC I • Alpha (heavy) chain + Beta micro-globulin• Ag groove within the alpha chain
• MHC II • Equivalent alpha and beta chains• Both chains combine to form the Ag groove
MHC Structure
•Class I alleles are more variable than WE had imagined!•Despite the variation inherent in MHC genes, interspecies variation of MHC class I alleles was overall in line with other dendrograms based on hemoglobin or cytochrome c•Investigation of the human HLA-A2 alpha chain using SIXFRAME and BLASTp analyses revealed alleles corresponding to both frame 1 and frame 3•ConSurf analysis indicated that the majority of variation at the peptide binding groove was in only one of the two alpha helices
Future Directions
•In the future, we would determine where the interspecies variation is highest one the MHC class I molecules.•We would also like to further define the relationship between HLA-A alleles and alleles of the other MHC class I loci (HLA-B and HLA-C).