Diel regulation of photosynthetic activity in the oceanic unicellular diazotrophic cyanobacterium Crocosphaera watsonii WH8501

0489049 - MBÚ 2019 RIV US eng J - Journal Article
Masuda, Takako - Bernát, Gábor - Bečková, Martina - Kotabová, Eva - Lawrenz, Evelyn - Lukeš, Martin - Komenda, Josef - Prášil, Ondřej
Diel regulation of photosynthetic activity in the oceanic unicellular diazotrophic cyanobacterium Crocosphaera watsonii WH8501.
Environmental Microbiology. Roč. 20, č. 2 (2018), s. 546-560. ISSN 1462-2912. E-ISSN 1462-2920
R&D Projects: GA MŠMT(CZ) LO1416; GA MŠMT(CZ) ED2.1.00/19.0392; GA ČR GA16-15467S
Institutional support: RVO:61388971
Keywords : NORTH PACIFIC-OCEAN * SYNECHOCYSTIS SP PCC-6803 * PHOTOSYSTEM-II
OECD category: Microbiology
Impact factor: 5.147, year: 2018

The oceanic unicellular diazotrophic cyanobacterium Crocosphaera watsonii WH8501 exhibits large diel changes in abundance of both Photosystem II (PSII) and Photosystem I (PSI). To understand the mechanisms underlying these dynamics, we assessed photosynthetic parameters, photosystem abundance and composition, and chlorophyll-protein biosynthesis over a diel cycle. Our data show that the decline in PSII activity and abundance observed during the dark period was related to a light-induced modification of PSII, which, in combination with the suppressed synthesis of membrane proteins, resulted in monomerization and gradual disassembly of a large portion of PSII core complexes. In the remaining population of assembled PSII monomeric complexes, we detected the non-functional version of the D1 protein, rD1, which was absent in PSII during the light phase. During the dark period, we also observed a significant decoupling of phycobilisomes from PSII and a decline in the chlorophyll a quota, which matched the complete loss of functional PSIIs and a substantial decrease in PSI abundance. However, the remaining PSI complexes maintained their photochemical activity. Thus, during the nocturnal period of nitrogen fixation C. watsonii operates a suite of regulatory mechanisms for efficient utilization/recycling of cellular resources and protection of the nitrogenase enzyme.
Permanent Link: http://hdl.handle.net/11104/0283534