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Bioinformaticians + Experimentalists = Successful Protein Analysis Katarzyna Poleszak International Institute of Molecular and Cell Biology Laboratory of Bioinformatics and Protein Engineering
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Research subjects Enzymes acting on: DNA RNA Discovering novel enzymes Protein engineering Characterization of protein complexes
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Structure of the laboratory Computer analysis Structure/function prediction Experimental validation
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What information do we get from protein structure? Protein function Biological processes Mechanism of reaction and interaction
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Discovering new RNA methyltransferases Elżbieta Purta
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Protein synthesis in bacteria Growing polypeptide Amino end Amino acid tRNA mRNA 50S rRNA: 5S rRNA 23S rRNA 30S rRNA: 16S rRNA
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Modified nucleosides in rRNA 11 modified nucleosides in 16S; 26 in 23S Main function: reinforce the tertiary structure essential for catalysis Other functions: resistance to antibiotics that bind to rRNA Modifying enzyme unknown Modifying enzyme identified in this lab
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YbeA: novel MTase specific for 23S rRNA +CH 3 (14Da) Mass spectrometry analysis
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Interaction of YbeA with the ribosome Katarzyna Kamińska
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Protein engineering of restriction endonucleases Sebastian Pawlak
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Restriction endonucleases (REases) occur frequently in bacteria and archaea cleave double-stranded DNA in a sequence-specific manner AACTGGCCTGCCA TTCACCGGACGGT dsDNAREase CCTGCCA GGACGGT AACTGG TTCACC cleaved DNA cleavage
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Why engineer REases? recombinant DNA technology diagnostic tool DNA physical mapping various cleaved sequences ~ 3700 REases 266 distinct specificities REBASE 2008 Important tools in biology:
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Increase in amount of discovered REases versus specificities 0 500 1000 1500 2000 2500 3000 3500 4000 19701975 1980 19851990199520002007 liczba specyficzności liczba ER number of specificities REases
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Bsp6I ? structure unknown Engineering of restriction endonuclease Bsp6I 5'5' GCNGC CGNCG 5'5' N = C, G, A, T
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Bsp6I model dr Janusz Bujnicki
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Predicted effect of Bsp6I mutagenesis No contact with middle bases Creating contact with middle bases G C N G C C G N C G G C N G C C G N C G E94 K
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Bsp6I with novel specificity GCNGC GCSGC GCCGC GCGGC GCWGC GCAGCGCTGC - + wtwt/R94K wtwt/R94K Activity [%]
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Characterization of protein complexes involved in DNA repair Katarzyna Poleszak
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Why study protein complexes involved in DNA repair? Protein-protein interactions Protein interaction sites Critical to most biological processes Potential drug targets Crucial to maintain genome stability DNA repairProcesses correcting DNA damages
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Analysing hMLH1-MBD4 interactions hMLH1 MBD4 MUTATION Hereditary nonpolyposis colorectal cancer (HNPCC) ? human MutL homolog Methyl binding domain
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Functions of MBD4 MBD4 Methyl binding domain Binds methylated DNA T/U glycosylase Tumor supresor
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Functions of hMLH1 Corects base-base mismatches Removes insertions and deletions hMLH1 human MutL homolog Depending on the interaction partner Recombination
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+ - Yeast two-hybrid system (Y2H)
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Screening protein-protein interactions Trp MBD-AD Leu hMLH1-BD Medium without Leu, Trp Medium without Leu, Trp, His Medium without Leu, Trp, His, Ade Cotransformation Weak interactions (HIS) Strong interactions (HIS, ADE)
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Prediction of hMLH1 protein interaction sites Jan Kosiński
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hMLH1 1498756 NTD N – terminal domain CTD C – terminal domain Ex domain In domain highly conserved less conserved involved in homo-, and heterodimerization human MutL homolog
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hMLH1 – MBD4 Y2H + + - +/-+/- - 1498 569677 wt hMLH1 1498756 1498 499555686756 498 499555569677686756 1 498 499555686756 569677 +/-+/- -
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hMLH1 mutations Jan Kosiński L574P P640S P648L P648S
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Measuring the strength of interaction -gal ONPG ortho-nitrophenol + galactose ONPG -gal
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hMLH1 mutants-MBD4 -galactosidase [U] ControlL574PE578GP640SP648LP648SY646C Relative strength of interaction hMLH1 mutants
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Mutations abolishing hMLH1-MBD4 interaction
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Summary Bioinformaticians + Experimentalists = Successful Protein Analysis
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www.genesilico.pl
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Acknowledgements Phd Janusz Bujnicki Phd Krzysztof Skowronek Elżbieta Purta Sebastian Pawlak Katarzyna Kamińska Jan Kosiński
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Thank you for your attention
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