PHOTOSYNTHESIS. A 12 Å carotenoid translocation in a photoswitch associated with cyanobacterial photoprotection

Science. 2015 Jun 26;348(6242):1463-6. doi: 10.1126/science.aaa7234.

Abstract

Pigment-protein and pigment-pigment interactions are of fundamental importance to the light-harvesting and photoprotective functions essential to oxygenic photosynthesis. The orange carotenoid protein (OCP) functions as both a sensor of light and effector of photoprotective energy dissipation in cyanobacteria. We report the atomic-resolution structure of an active form of the OCP consisting of the N-terminal domain and a single noncovalently bound carotenoid pigment. The crystal structure, combined with additional solution-state structural data, reveals that OCP photoactivation is accompanied by a 12 angstrom translocation of the pigment within the protein and a reconfiguration of carotenoid-protein interactions. Our results identify the origin of the photochromic changes in the OCP triggered by light and reveal the structural determinants required for interaction with the light-harvesting antenna during photoprotection.

Publication types

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

MeSH terms

  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / metabolism
  • Canthaxanthin / chemistry*
  • Canthaxanthin / metabolism
  • Crystallography, X-Ray
  • Models, Chemical
  • Photosynthesis*
  • Phycobilisomes / chemistry*
  • Protein Structure, Secondary
  • Protein Transport
  • Synechocystis / metabolism*

Substances

  • Bacterial Proteins
  • Phycobilisomes
  • orange carotenoid protein, Synechocystis
  • Canthaxanthin

Associated data

  • PDB/4XB4
  • PDB/4XB5