PSB33 sustains photosystem II D1 protein under fluctuating light conditions

Rikard Fristedt, Andrea Trotta, Marjaana Suorsa, Anders K. Nilsson, Roberta Croce, Eva Mari Aro, Björn Lundin*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


On Earth, solar irradiance varies as the sun rises and sets over the horizon, and sunlight is thus in constant fluctuation, following a slow dark–low–high–low–dark curve. Optimal plant growth and development are dependent on the capacity of plants to acclimate and regulate photosynthesis in response to these changes of light. Little is known of regulative processes for photosynthesis during nocturnal events. The nucleus-encoded plant lineage-specific protein PSB33 has been described as stabilizing the photosystem II complex, especially under light stress conditions, and plants lacking PSB33 have a dysfunctional state transition. To clarify the localization and function of this protein, we used phenomic, biochemical and proteomics approaches in the model plant Arabidopsis. We report that PSB33 is predominantly located in non-appressed thylakoid regions and dynamically associates with a thylakoid protein complex in a light-dependent manner. Moreover, plants lacking PSB33 show an accelerated D1 protein degradation in nocturnal periods, and show severely stunted growth when challenged with fluctuating light. We further show that the function of PSB33 precedes the STN7 kinase to regulate or balance the excitation energy of photosystems I and II in fluctuating light conditions.

Original languageEnglish
Pages (from-to)4281-4293
Number of pages13
JournalJournal of Experimental Botany
Issue number15
Publication statusPublished - 10 Jul 2017


This research was financially supported by the Carl Tryggers foundation to BL and AN and the Academy of Finland (project numbers 272424, 271832 and 273870). RF was supported by the ERC consolidator grant 281341 to RC. The Proteomics Facility of the Turku Centre for Biotechnology is acknowledged for their excellent support in mass spectrometry.

FundersFunder number
Carl Tryggers foundation
ERC Consolidator
Seventh Framework Programme281341
Academy of Finland273870, 272424, 271832


    • Arabidopsis
    • Chloroplast
    • Fluctuating lights
    • Photosynthesis
    • PSB33
    • PSII
    • Quality control of PSII
    • State transition


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