A1 Refereed original research article in a scientific journal
Photodamage of iron-sulphur clusters in photosystem I induces non-photochemical energy dissipation
Authors: Arjun Tiwari, Fikret Mamedov, Michele Grieco, Marjaana Suorsa, Anjana Jajoo, Stenbjörn Styring, Mikko Tikkanen, Eva-Mari Aro
Publisher: NATURE PUBLISHING GROUP
Publishing place: Karlsruhe
Publication year: 2016
Journal: Nature Plants
Journal name in source: NATURE PLANTS
Journal acronym: NAT PLANTS
Article number: ARTN 16035
Volume: 2
Issue: 4
Number of pages: 9
ISSN: 2055-026X
eISSN: 2055-0278
DOI: https://doi.org/10.1038/NPLANTS.2016.35(external)
Photosystem I (PSI) uses light energy and electrons supplied by photosystem II (PSII) to reduce NADP(+) to NADPH. PSI is very tolerant of excess light but extremely sensitive to excess electrons from PSII. It has been assumed that PSI is protected from photoinhibition by strict control of the intersystem electron transfer chain (ETC). Here we demonstrate that the iron-sulphur (FeS) clusters of PSI are more sensitive to high light stress than previously anticipated, but PSI with damaged FeS clusters still functions as a non-photochemical photoprotective energy quencher (PSI-NPQ). Upon photoinhibition of PSI, the highly reduced ETC further triggers thylakoid phosphorylation-based mechanisms that increase energy flow towards PSI. It is concluded that the sensitivity of FeS clusters provides an additional photoprotective mechanism that is able to downregulate PSII, based on PSI quenching and protein phosphorylation.
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