@article{4d089f6663a548719b1d4a094857f254,
title = "The multiplicity of roles for (bi)carbonate in photosystem II operation in the hypercarbonate-requiring cyanobacterium Arthrospira maxima",
abstract = "Arthrospira maxima is unique among cyanobacteria, growing at alkaline pH (<11) in concentrated (bi)carbonate (1.2 M saturated) and lacking carbonic anhydrases. We investigated dissolved inorganic carbon (DIC) roles within PSII of A. maxima cells oximetrically and fluorometrically, monitoring the light reactions on the donor and acceptor sides of PSII. We developed new methods for removing DIC based on a (bi)carbonate chelator and magnesium for (bi)carbonate ionpairing. We established relative affinities of three sites: the water-oxidizing complex (WOC), non-heme iron/QA–, and solvent-accessible arginines throughout PSII. Full reversibility is achieved but (bi)carbonate uptake requires light. DIC depletion at the non-heme iron site and solvent-accessible arginines greatly reduces the yield of O2 due to O2 uptake, but accelerates the PSII–WOC cycle, specifically the S2→S3 and S3→S0 transitions. DIC removal from the WOC site abolishes water oxidation and appears to influence free energy stabilization of the WOC from a site between CP43-R357 and Ca2+.",
keywords = "bicarbonate depletion, dissolved inorganic carbon, oxygen-evolving complex, redox tuning, water-oxidizing complex",
author = "G. Ananyev and C. Gates and Dismukes, {G. C.}",
note = "Funding Information: Received 23 May 2017, accepted 8 September 2017, published as online-first 15 January 2018. +Corresponding author; e-mail: dismukes@rutgers.edu Abbreviations: alpha – miss; beta – double hit; Chl – chlorophyll; delta – backward transition; DIC – dissolved inorganic carbon; DMBQ – 2,5-dimethyl-p-benzoquinone; epsilon – deactivation; F0 – minimal fluorescence yield of the dark-adapted state; Fm – maximal fluorescence yield of the dark-adapted state; FRRF – fast repetition rate fluorometry; Fv – variable fluorescence; Fv/Fm – maximal quantum yield of PSII photochemistry; PET – photosynthetic electron transport; PQ – plastoquinone; S0–S4 – oxidation states of the WOC, “S-states”; VZAD (model) – Vinyard-Zachary-Ananyev-Dismukes model; WOC – water oxidizing complex; Yss – steady-state yield. Acknowledgements: This work was funded by the Department of Energy, Basic Energy Sciences, Grant DE-FG02-10ER16195, and by the Stanford University Global Climate and Energy Project, activity number 96. We thank Dr. Dmitry Shevela for constructive advice and previous research, Prof. A. W. Rutherford for research which provided a foundation for our own work, and Prof. Govindjee for a long lifetime of progress on this subject and a great deal of prior advice. ‡Dedicated to Prof. Govindjee on the occasion of his 85th birthday. Publisher Copyright: {\textcopyright} 2018, The Institute of Experimental Botany.",
year = "2018",
month = mar,
day = "1",
doi = "10.1007/s11099-018-0781-0",
language = "English (US)",
volume = "56",
pages = "217--228",
journal = "Photosynthetica",
issn = "0300-3604",
publisher = "Springer Netherlands",
number = "1",
}