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Ascorbate accumulation during sulphur deprivation and its effects on photosystem II activity and H production of the green alga Chlamydomonas reinhardtii.

Nagy, Valéria and Vidal-Meireles, A. and Tengölics, Roland and Rákhely, Gábor and Garab, Győző and Kovács, László and Tóth, Szilvia Zita (2016) Ascorbate accumulation during sulphur deprivation and its effects on photosystem II activity and H production of the green alga Chlamydomonas reinhardtii. PLANT CELL AND ENVIRONMENT. pp. 1-34. ISSN 0140-7791

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Abstract

In nature, H2 production in Chlamydomonas reinhardtii serves as a safety valve during the induction of photosynthesis in anoxia and it prevents the over-reduction of the photosynthetic electron transport chain. Sulphur deprivation of C. reinhardtii also triggers a complex metabolic response resulting in the induction of various stress-related genes, downregulation of photosynthesis, the establishment of anaerobiosis and expression of active hydrogenase. Photosystem II (PSII) plays dual role in H2 production because it supplies electrons but the evolved O2 inhibits the hydrogenase. Here we show that upon sulphur deprivation the ascorbate content in C. reinhardtii increases about 100-fold, reaching the mM range; at this concentration ascorbate inactivates the Mn-cluster of PSII and afterwards it can donate electrons to tyrozin Z+ at a slow rate. This stage is followed by donor-side induced photoinhibition, leading to the loss of charge separation activity in PSII and reaction center degradation. The time point at which maximum ascorbate concentration is reached in the cell is critical for the establishment of anaerobiosis and initiation of H2 production. We also show that ascorbate influenced H2 evolution via altering the photosynthetic electron transport rather than hydrogenase activity and starch degradation.

Item Type: Article
Subjects: Q Science / természettudomány > QH Natural history / természetrajz > QH301 Biology / biológia > QH3011 Biochemistry / biokémia
Q Science / természettudomány > QK Botany / növénytan > QK10 Plant physiology / növényélettan
S Agriculture / mezőgazdaság > SB Plant culture / növénytermesztés
SWORD Depositor: MTMT SWORD
Depositing User: MTMT SWORD
Date Deposited: 22 Jan 2016 08:06
Last Modified: 20 Jan 2017 00:15
URI: http://real.mtak.hu/id/eprint/32629

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