Local and global structural drivers for the photoactivation of the orange carotenoid protein

Sayan Gupta, Miklos Guttman, Ryan L. Leverenz, Kulyash Zhumadilova, Emily G. Pawlowski, Christopher J. Petzold, Kelly K. Lee, Corie Y. Ralston, Cheryl A. Kerfeld

Research output: Contribution to journalArticlepeer-review

77 Citations (Scopus)


Photoprotective mechanisms are of fundamental importance for the survival of photosynthetic organisms. In cyanobacteria, the orange carotenoid protein (OCP), when activated by intense blue light, binds to the light-harvesting antenna and triggers the dissipation of excess captured light energy. Using a combination of small angle X-ray scattering (SAXS), X-ray hydroxyl radical footprinting, circular dichroism, and H/D exchange mass spectrometry, we identified both the local and global structural changes in the OCP upon photoactivation. SAXS and H/D exchange data showed that global tertiary structural changes, including complete domain dissociation, occur upon photoactivation, but with alteration of secondary structure confined to only the N terminus of the OCP. Microsecond radiolytic labeling identified rearrangement of the H-bonding network associated with conserved residues and structural water molecules. Collectively, these data provide experimental evidence for an ensemble of local and global structural changes, upon activation of the OCP, that are essential for photoprotection.

Original languageEnglish
Pages (from-to)E5567-E5574
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number41
Publication statusPublished - Oct 13 2015


  • Hydrogen deuterium exchange
  • Orange carotenoid protein
  • Photoprotection
  • SAXS
  • X-ray footprinting

ASJC Scopus subject areas

  • General

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