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Structural biology should be computable! Protein structures determined by amino acid sequences Protein structures and complexes correspond to global free energy minima Fundamental test of understanding and huge practical relevance
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Model of energetics of inter and intramolecular interactions Design (Given Structure, Optimize Sequence) Prediction (Given Sequence, Optimize Structure) Ab initio structure Protein Structure Protein design prediction Protein-protein docking Protein-protein Interface design interactions ROSETTA
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Model of macromolecular interactions Removal of single methyl groups can destabilize proteins --> jigsaw puzzle-like packing crucial Buried polar atoms almost always hydrogen bonded --> treat hydrogen bonding as accurately as possible Exposed charge substitutions generally have little effect --> damp long range elctrostatics Focus on short range interactions!
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Random Start Low-Resolution Monte Carlo Search (integrate out sidechain degrees of freedom) High-Resolution Refinement with full atomic detail 10 5 Predictions Conformational sampling Select lowest energy models Jeff Gray (Hopkins), Ora Furman (Hebrew University), Chu Wang
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Docking Low-Resolution Search Monte Carlo Search Rigid body translations and rotations Residue-scale interaction potentials Protein representation: backbone atoms + average centroids
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Docking Protocol (Target 12: cohesin-dockerin; unbound-bound) 1.Initial Search2.Refinement RMSD to arbitrary starting structure Energy RMSD to starting structure of refinement (Å)
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red,orange– xray blue – model; green – unbound 0.46Å interface rmsd 87% native contacts 6% wrong contacts Target 12 Cohesin-Dockerin Side Chain Flexibility dockerin cohesin Ora Furman, Chu Wang
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Details of T12 Interface D39 N37 S45 L83 E86 Y74 L22 R53 dockerin cohesin red,orange– xray blue - model
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red,orange– xray blue - model 0.23Å interface rmsd Target 15 immunity protein D- colicin D tRNase Accurate Side Chain Modeling colicin immunity protein Science 310, 638-642
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Details of T15 Interface H611 red,orange– xray blue - model E56 K610 K608 K607 E68 E59 D61 colicin immunity protein
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red,orange– xray blue – model; green – unbound 2.34Å interface rmsd 36% native contacts Target 20 HemK-RF1 Modeling Backbone Movement RF1 HemK Loop with methylated Gln Chu Wang
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CASP6 T0198: PhoU domain repeat Model 2: 4A over 210 rsds (Model 1: 3.94 over 198) Phil Bradley
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CASP6 T0212 Model 2: 3.97 over 109 rsds (Model 1: 4.0 over 104)
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T0281 ab initio prediction (1.59Å) Phil Bradley
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1r69
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1ubq Science 309, 1868-1871
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2REB
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Boinc.bakerlab.org/rosetta David Kim High resolution ab initio structure prediction from single sequences by enhanced diversity “barcode” directed sampling Outreach!
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High Resolution Refinement of CASP target 199 - remote homology model Calculations performed on SDSC teragrid clusters Bin Qian
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High Resolution NMR Model Refinement Vatson Raman Disulfide Bond Formation Protein Blue - X-ray structure Green - NMR models Red - Rosetta models
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Computing Structural Biology Free energy function reasonable => Computing simple protein structures and interactions now appears to be within reach Implications for structural genomics? More cpu power => more accurate predictions for larger proteins For larger complexes, experimental data essential (low resolution electron density!). Symmetry helps! Modeling accuracy also illustrated by structures of designed proteins
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Top7 X-ray structure has correct topology. Backbone RMSD to design only 1.2Å!! C- Backbone Overlay Red : X-ray structure Blue : Design model Brian Kuhlman, Gautam Dantas; Science 302 1364-8
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Design of novel H bond network interface G177 Q51 Q180 Q169 Y35 G177 Q180 Q169 Q51 Y35 G177 Y35 Design X-ray Lukasz Joachimiak
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Design of new protein functions Design of new protein-protein interactions Design of enzymes catalyzing novel chemical reactions Design of new transcription factor and endonuclease specificities Design of HIV vaccine
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HIV vaccine design Present HIV coat protein epitopes locked into conformation observed in complexes with neutralizing antibodies using designed scaffolds Preliminary results: designed proteins fold and bind neutralizing antibodies (5nM affinity). One design confirmed crystallographically. Bill Schief in collaboration with Peter Kwong
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Crystal structure of Mab 2F5 in complex with its HIV epitope Model of non-HIV scaffold-epitope (red) Computational design of non-HIV immunogens to elicit broadly-neutralizing antibodies Bill Schief
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WT-WT Design-WT WT-Design Design-Design Redesign of DNA cleavage specificity of MsoI homing endonuclease using ROSETTA Justin Ashworth, Jim Havranek Nature in press
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Specific DNA cleavage by designed nuclease wild-type I-Mso Design - 1/2 n 1 wild-type design wild-type design Cleavage targets ½¼ - 1/2 9 5uM nuclease
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Acknowledgements Design Brian Kuhlman (UNC) Gautam Dantas Justin Ashworth Jim Havranek Robetta.bakerlab.org prediction and design server: David Kim (domain parsing, boinc) and Dylan Chivian Rosetta software freely available for academic use Boinc.bakerlab.org/rosetta Protein structure prediction Phil Bradley (MIT) Rhiju Das Lars Marlstrom Bin Qian Vatson Raman Protein-protein docking Ora Furman (Hebrew University) Chu Wang Jeff Gray (Johns Hopkins)
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