Structural basis for the adaptation and function of chlorophyll f in photosystem I

Nat Commun. 2020 Jan 13;11(1):238. doi: 10.1038/s41467-019-13898-5.

Abstract

Chlorophylls (Chl) play pivotal roles in energy capture, transfer and charge separation in photosynthesis. Among Chls functioning in oxygenic photosynthesis, Chl f is the most red-shifted type first found in a cyanobacterium Halomicronema hongdechloris. The location and function of Chl f in photosystems are not clear. Here we analyzed the high-resolution structures of photosystem I (PSI) core from H. hongdechloris grown under white or far-red light by cryo-electron microscopy. The structure showed that, far-red PSI binds 83 Chl a and 7 Chl f, and Chl f are associated at the periphery of PSI but not in the electron transfer chain. The appearance of Chl f is well correlated with the expression of PSI genes induced under far-red light. These results indicate that Chl f functions to harvest the far-red light and enhance uphill energy transfer, and changes in the gene sequences are essential for the binding of Chl f.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Chlorophyll / analogs & derivatives*
  • Chlorophyll / metabolism
  • Chlorophyll / radiation effects
  • Chlorophyll A / metabolism
  • Chlorophyll A / radiation effects
  • Cryoelectron Microscopy
  • Cyanobacteria / chemistry
  • Cyanobacteria / physiology
  • Energy Transfer
  • Light
  • Models, Molecular
  • Photosystem I Protein Complex / chemistry*
  • Photosystem I Protein Complex / metabolism*
  • Photosystem I Protein Complex / radiation effects
  • Protein Conformation

Substances

  • Photosystem I Protein Complex
  • chlorophyll f
  • Chlorophyll
  • Chlorophyll A