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Daniel Russel and Leonidas Guibas Stanford University. Exploring Protein Folding Trajectories Using Geometric Spanners. Goals. Existing work understanding protein structure Classification Comparison Matching Qualitative understanding of proteins motions We do not quite get there yet.
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Daniel Russel and Leonidas Guibas Stanford University Exploring Protein Folding Trajectories Using Geometric Spanners
Goals • Existing work understanding protein structure • Classification • Comparison • Matching • Qualitative understanding of proteins motions • We do not quite get there yet
Outline • Overview of spanners • Properties of interest • Displaying trajectories • Future work
Geometric Spanners • Vertexes are points • Edges have length • Expansion factor • Ratio between graph distanceand Euclidean distance
Geometric Spanners • Vertexes are points • Edges have length • Expansion factor • Ratio between graph distanceand Euclidean distance
2CI2 Spanner backbone atom index backbone atom index Expansion factor is 2 Expansion factor is 2 spanner edges
2CI2 Spanner: Helix backbone atom index ahelix backbone atom index
2CI2 Spanner: Strands backbone atom index parallel strands backbone atom index antiparallel strands
2CI2 Spanner: Tertiary Structure backbone atom index backbone atom index tertiary interactions
Outline • Overview of spanners • Properties of interest • Displaying trajectories • Future work
Combinatorializes Structure • Picks a few pairs per set of adjacencies
Other Properties • Regular structure of helices and strands • Local meaning for edge
Family of Descriptors • Vary expansion factor • From distance matrix to sparse • Linear for many values 1.5 1.75 2.0 2.5 3.0
Outline • Overview of spanners • Properties of interest • Displaying trajectories • Future work
Protein Folding Trajectories • Input: Protein trajectories • Currently small proteins, later larger • Nanosecond timescales, later millisecond • Tens or hundreds of folding trajectories • Many non-folding • Want to understand • Individual trajectories • Structure of conformation space
Processing Spanners • Edges move slightly between frames • Tracked edge some matching pairs initial frame edges final frame edges identical edges (identical edges coloredgreyormagenta)
Another View backbone index Initial edges Final edges
Smoothing • Birth and death events • Persistent edges • Gaps Tracked edge persistent edges Birth Death time
Strip Spanner Representation length start vertex
Strip History brighten edge length frame index along backbone
Segmenting Trajectories segmentdividers sample conformation
Example: BBA5 (1) (3) Native state (2)
Outline • Overview of spanners • Properties of interest • Displaying trajectories • Future work
Sidechains • Breaks the ordering of nodes • How many points?
Comparing Motions • Compare pairs of trajectories • Partial matches • Cluster conformations • Find bottlenecks • Cluster trajectories • Which are similar • Which are unique
Deeper Understanding • Proteins → spanner • Graph → proteins • Spanner distances vs. conformation distances