Evolutionary capacitance and control of protein stability in protein-protein interaction networks

PLoS Comput Biol. 2013 Apr;9(4):e1003023. doi: 10.1371/journal.pcbi.1003023. Epub 2013 Apr 4.

Abstract

In addition to their biological function, protein complexes reduce the exposure of the constituent proteins to the risk of undesired oligomerization by reducing the concentration of the free monomeric state. We interpret this reduced risk as a stabilization of the functional state of the protein. We estimate that protein-protein interactions can account for ~2-4 k(B)T of additional stabilization; a substantial contribution to intrinsic stability. We hypothesize that proteins in the interaction network act as evolutionary capacitors which allows their binding partners to explore regions of the sequence space which correspond to less stable proteins. In the interaction network of baker's yeast, we find that statistically proteins that receive higher energetic benefits from the interaction network are more likely to misfold. A simplified fitness landscape wherein the fitness of an organism is inversely proportional to the total concentration of unfolded proteins provides an evolutionary justification for the proposed trends. We conclude by outlining clear biophysical experiments to test our predictions.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Computational Biology / methods*
  • Cytoplasm / chemistry
  • Evolution, Molecular*
  • Fungal Proteins / chemistry*
  • HSP90 Heat-Shock Proteins / chemistry
  • Protein Binding
  • Protein Conformation
  • Protein Denaturation
  • Protein Folding
  • Protein Interaction Mapping / methods*
  • Protein Interaction Maps*
  • Proteins / chemistry*
  • Saccharomyces cerevisiae / chemistry
  • Thermodynamics

Substances

  • Fungal Proteins
  • HSP90 Heat-Shock Proteins
  • Proteins

Grants and funding

This work was funded by the DOE Systems Biology KBase university-led project “Tools and Models for Integrating Multiple Cellular Networks” (http://genomicscience.energy.gov/compbio/kbaseprojects.shtml). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.