title: A simple dependence between protein evolution rate and the number of protein-protein interactions.
abstract: BACKGROUND
  It has been shown for an evolutionarily distant genomic comparison that the number of protein-protein interactions a protein has correlates negatively with their rates of evolution. However, the generality of this observation has recently been challenged. Here we examine the problem using protein-protein interaction data from the yeast Saccharomyces cerevisiae and genome sequences from two other yeast species.
  
  
  RESULTS
  In contrast to a previous study that used an incomplete set of protein-protein interactions, we observed a highly significant correlation between number of interactions and evolutionary distance to either Candida albicans or Schizosaccharomyces pombe. This study differs from the previous one in that it includes all known protein interactions from S. cerevisiae, and a larger set of protein evolutionary rates. In both evolutionary comparisons, a simple monotonic relationship was found across the entire range of the number of protein-protein interactions. In agreement with our earlier findings, this relationship cannot be explained by the fact that proteins with many interactions tend to be important to yeast. The generality of these correlations in other kingdoms of life unfortunately cannot be addressed at this time, due to the incompleteness of protein-protein interaction data from organisms other than S. cerevisiae.
  
  
  CONCLUSIONS
  Protein-protein interactions tend to slow the rate at which proteins evolve. This may be due to structural constraints that must be met to maintain interactions, but more work is needed to definitively establish the mechanism(s) behind the correlations we have observed.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA. hunter@ocf.berkeley.edu
authors.forename: Hunter B
authors.initials: HB
authors.lastname: Fraser
authors.forename: Dennis P
authors.initials: DP
authors.lastname: Wall
authors.forename: Aaron E
authors.initials: AE
authors.lastname: Hirsh
mesh_terms: D002176:Candida albicans / Q000235:genetics; D019143:Evolution, Molecular; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D016681:Genome, Fungal; D011485:Protein Binding / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D012568:Schizosaccharomyces / Q000235:genetics; D015003:Yeasts / Q000235:genetics*
chemical_list: D005656:Fungal Proteins