Multi-Objective Stochastic Search for Sampling Local Minima in the Protein Energy Surface

  • Authors:
  • Brian Olson;Amarda Shehu

  • Affiliations:
  • Department of Computer Science, George Mason University, Fairfax, VA 22030;Department of Computer Science, Department of Bioengineering, School of Systems Biology, George Mason University, Fairfax, VA 22030

  • Venue:
  • Proceedings of the International Conference on Bioinformatics, Computational Biology and Biomedical Informatics
  • Year:
  • 2013

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Abstract

We present an evolutionary stochastic search algorithm to obtain a discrete representation of the protein energy surface in terms of an ensemble of conformations representing local minima. This objective is of primary importance in protein structure modeling, whether the goal is to obtain a broad view of potentially different structural states thermodynamically available to a protein system or to predict a single representative structure of a unique functional native state. In this paper, we focus on the latter setting, and show how approaches from evolutionary computation for effective stochastic search and multi-objective analysis can be combined to result in protein conformational search algorithms with high exploration capability. From a broad computational perspective, the contributions of this paper are on how to balance global and local search of some high-dimensional search space and how to guide the search in the presence of a noisy, inaccurate scoring function. From an application point of view, the contributions are demonstrated in the domain of template-free protein structure prediction on the primary subtask of sampling diverse low-energy decoy conformations of an amino-acid sequence. Comparison with the approach used for decoy sampling in the popular Rosetta protocol on 20 diverse protein sequences shows that the evolutionary algorithm proposed in this paper is able to access lower-energy regions with similar or better proximity to the known native structure.