A complex containing PGRL1 and PGR5 is involved in the switch between linear and cyclic electron flow in Arabidopsis

Cell. 2008 Jan 25;132(2):273-85. doi: 10.1016/j.cell.2007.12.028.


During photosynthesis, two photoreaction centers located in the thylakoid membranes of the chloroplast, photosystems I and II (PSI and PSII), use light energy to mobilize electrons to generate ATP and NADPH. Different modes of electron flow exist, of which the linear electron flow is driven by PSI and PSII, generating ATP and NADPH, whereas the cyclic electron flow (CEF) only generates ATP and is driven by the PSI alone. Different environmental and metabolic conditions require the adjustment of ATP/NADPH ratios and a switch of electron distribution between the two photosystems. With the exception of PGR5, other components facilitating CEF are unknown. Here, we report the identification of PGRL1, a transmembrane protein present in thylakoids of Arabidopsis thaliana. Plants lacking PGRL1 show perturbation of CEF, similar to PGR5-deficient plants. We find that PGRL1 and PGR5 interact physically and associate with PSI. We therefore propose that the PGRL1-PGR5 complex facilitates CEF in eukaryotes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / biosynthesis
  • Amino Acid Sequence
  • Arabidopsis / genetics
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Chloroplasts / metabolism
  • DNA, Plant / genetics
  • DNA, Plant / isolation & purification
  • Electron Transport
  • Gene Expression Regulation, Plant
  • Genes, Plant
  • Kinetics
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Models, Biological
  • Molecular Sequence Data
  • Mutation
  • NADP / biosynthesis
  • Oxidation-Reduction
  • Photosynthetic Reaction Center Complex Proteins / genetics
  • Photosynthetic Reaction Center Complex Proteins / metabolism*
  • Photosystem I Protein Complex / metabolism*
  • Plastoquinone / metabolism
  • Protein Isoforms / chemistry
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Subcellular Fractions / metabolism
  • Thylakoids / chemistry*


  • Arabidopsis Proteins
  • DNA, Plant
  • Membrane Proteins
  • PGR5 protein, Arabidopsis
  • PGRL1 protein, Arabidopsis
  • Photosynthetic Reaction Center Complex Proteins
  • Photosystem I Protein Complex
  • Protein Isoforms
  • Recombinant Fusion Proteins
  • NADP
  • Adenosine Triphosphate
  • Plastoquinone