Hypergraph model of multi-residue interactions in proteins: sequentially–constrained partitioning algorithms for optimization of site-directed protein recombination

  • Authors:
  • Xiaoduan Ye;Alan M. Friedman;Chris Bailey-Kellogg

  • Affiliations:
  • Department of Computer Science, Dartmouth College, Hanover, NH;Department of Biological Sciences and Purdue Cancer Center, Purdue University, West Lafayette, IN;Department of Computer Science, Dartmouth College, Hanover, NH

  • Venue:
  • RECOMB'06 Proceedings of the 10th annual international conference on Research in Computational Molecular Biology
  • Year:
  • 2006

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Abstract

Relationships among amino acids determine stability and function and are also constrained by evolutionary history. We develop a probabilistic hypergraph model of residue relationships that generalizes traditional pairwise contact potentials to account for the statistics of multi-residue interactions. Using this model, we detected non-random associations in protein families and in the protein database. We also use this model in optimizing site-directed recombination experiments to preserve significant interactions and thereby increase the frequency of generating useful recombinants. We formulate the optimization as a sequentially-constrained hypergraph partitioning problem; the quality of recombinant libraries wrt a set of breakpoints is characterized by the total perturbation to edge weights. We prove this problem to be NP-hard in general, but develop exact and heuristic polynomial-time algorithms for a number of important cases. Application to the beta-lactamase family demonstrates the utility of our algorithms in planning site-directed recombination.