Identification of new factors in the stable accumulation of the PSII complexes

February 22, 2018

Contributes to further dissection of the mechanism for PSII assembly in plants

Photosynthesis is a very complicated biochemical process and is not yet fully understood. In particular, many questions remain about the complicated nature of de novo synthesis of photosystem II (PSII) and its repair following photodamage under excessive light. The light- harvesting chlorophyll a/b-binding (LHC) protein complexes associated with PSII absorbs light and provides energy for photosynthesis. On the other hand, light-harvesting-like (Lil) proteins are believed to be involved in photoprotection instead of harvesting light energy, but their function is not well understood.

An international collaborative group from RIKEN CSRS, Hokkaido University, Japan Women’s University, and Sweden’s Umea University have discovered new factors involved in the early step of PSII assembly in Arabidopsis.

The group analyzed plants deficient in the one-helix proteins OHP1 and OHP2 (which are Lil proteins with one transmembrane helix), clarifying that these proteins are essential to the molecular assembly of PSII core proteins. They also discovered that OHP1 forms protein complexes with both OHP2 and HCF244 (a putative homolog of cyanobacterial Ycf39), and associates with the PSII core proteins D1/D2, HCF136, HCF173 and a few other plant-specific proteins. The findings indicate that the OHP1/OHP2-HCF244 complex plays an important role in the PSII assembly process.

Various abiotic stress conditions such as drought and low-temperature much reduce the photosynthetic activity because PSII cannot be synthesized. Further development of this research is expected to be useful for the improvement of crops that can maintain photosynthesis under stressful circumstances.

Original article
Plant Physiology doi:10.1104/pp.17.01782
F. Myouga, K. Takahashi, R. Tanaka, N. Nagata, A. Z. Kiss, C. Funk, Y. Nomura, H. Nakagami, S. Jansson, K. Shinozaki,
"Stable accumulation of photosystem II requires ONE-HELIX PROTEIN1 (OHP1) of the light harvesting-like family".
Kazuo Shinozaki; Group Director
Fumiyoshi Myouga; Research Scientist
Gene Discovery Research Group