Tight association of phycobilisome and photosystem I complexes induced under iron-deficient conditions

July 03, 2023

Researchers at Shizuoka University, together with those at Okayama University and the RIKEN CSRS, successfully purified two types of supercomplexes, PSI-monomer-PBS and PSI-dimer-PBS supercomplexes, of which phycobilisomes (PBSs) bind to photosystem I (PSI), from the cyanobacterium Anabaena sp. PCC 7120 (Anabaena) grown under iron-deficient conditions and identified their molecular characteristics. Purifying PSI-PBS supercomplexes under normal iron-replete culture conditions is challenging, probably because of the weak interaction between these two compounds. This study is the first to discover that iron-deficient conditions induce a tight association between PBSs and PSI.

Almost all cyanobacteria have PBSs and contribute to harvesting sunlight. It remains to be elucidated whether the iron-deficiency-enhanced interaction between PBSs and PSI found in this study is common to many cyanobacteria species or unique to Anabaena. Understanding such an unknown molecular mechanism triggered by a lack of nutrients would lead to research into the adaptive mechanism of light harvesting in photosynthetic organisms.

Original article
Biochimica et Biophysica Acta - Bioenergetics doi: 10.1016/j.bbabio.2023.148993
S. Shimizu, H. Ogawa, N. Tsuboshita, T. Suzuki, K. Kato, Y. Nakajima, N. Dohmae, J.-R. Shen, R. Nagao,
"Tight association of CpcL with photosystem I in Anabaena sp. PCC 7120 grown under iron-deficient conditions".
Naoshi Dohmae
Unit Leader
Biomolecular Characterization Unit