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Nitric Oxide Remodels the Photosynthetic Apparatus upon S-Starvation in Chlamydomonas reinhardtii

TitleNitric Oxide Remodels the Photosynthetic Apparatus upon S-Starvation in Chlamydomonas reinhardtii
Publication TypeJournal Article
Year of Publication2019
AuthorsDe Mia, M, Lemaire, SD, Choquet, Y, Wollman, FA
JournalPlant Physiol
Date PublishedFeb
ISBN Number1532-2548 (Electronic)0032-0889 (Linking)
KeywordsChlamydomonas reinhardtii/drug effects/*physiology, Chloroplast Proteins/metabolism, Cytochrome b6f Complex/metabolism, Light, Nitric Oxide Donors/pharmacology, Nitric Oxide/*metabolism, Peptide Hydrolases/metabolism, Photosynthesis/*physiology, Plant Proteins/metabolism, Ribulose-Bisphosphate Carboxylase/metabolism, Signal Transduction, Sulfur/*metabolism

Many photosynthetic autotrophs have evolved responses that adjust their metabolism to limitations in nutrient availability. Here we report a detailed characterization of the remodeling of photosynthesis upon sulfur starvation under heterotrophy and photo-autotrophy in the green alga (Chlamydomonas reinhardtii). Photosynthetic inactivation under low light and darkness is achieved through specific degradation of Rubisco and cytochrome b 6 f and occurs only in the presence of reduced carbon in the medium. The process is likely regulated by nitric oxide (NO), which is produced 24 h after the onset of starvation, as detected with NO-sensitive fluorescence probes visualized by fluorescence microscopy. We provide pharmacological evidence that intracellular NO levels govern this degradation pathway: the addition of a NO scavenger decreases the rate of cytochrome b 6 f and Rubisco degradation, whereas NO donors accelerate the degradation. Based on our analysis of the relative contribution of the different NO synthesis pathways, we conclude that the NO2-dependent nitrate reductase-independent pathway is crucial for NO production under sulfur starvation. Our data argue for an active role for NO in the remodeling of thylakoid protein complexes upon sulfur starvation.

Short TitlePlant physiology

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