The origins of novel protein interactions during animal opsin evolution

PLoS One. 2007 Oct 17;2(10):e1054. doi: 10.1371/journal.pone.0001054.


Background: Biologists are gaining an increased understanding of the genetic bases of phenotypic change during evolution. Nevertheless, the origins of phenotypes mediated by novel protein-protein interactions remain largely undocumented.

Methodology/principle findings: Here we analyze the evolution of opsin visual pigment proteins from the genomes of early branching animals, including a new class of opsins from Cnidaria. We combine these data with existing knowledge of the molecular basis of opsin function in a rigorous phylogenetic framework. We identify adaptive amino acid substitutions in duplicated opsin genes that correlate with a diversification of physiological pathways mediated by different protein-protein interactions.

Conclusions/significance: This study documents how gene duplication events early in the history of animals followed by adaptive structural mutations increased organismal complexity by adding novel protein-protein interactions that underlie different physiological pathways. These pathways are central to vision and other photo-reactive phenotypes in most extant animals. Similar evolutionary processes may have been at work in generating other metazoan sensory systems and other physiological processes mediated by signal transduction.

Publication types

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

MeSH terms

  • Animals
  • Cnidaria / metabolism
  • Evolution, Molecular*
  • In Situ Hybridization
  • Light
  • Likelihood Functions
  • Markov Chains
  • Models, Biological
  • Phenotype
  • Phylogeny
  • Protein Interaction Mapping*
  • Rod Opsins / chemistry*
  • Rod Opsins / genetics
  • Rod Opsins / physiology*
  • Signal Transduction
  • Species Specificity


  • Rod Opsins