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  • Accepted Manuscript: Chloroplast ATP Synthase Modulation of the Thylakoid Proton Motive Force: Implications for Photosystem I and Photosystem II Photoprotection

Title: Chloroplast ATP Synthase Modulation of the Thylakoid Proton Motive Force: Implications for Photosystem I and Photosystem II Photoprotection

In wild type plants, decreasing CO 2 lowers the activity of the chloroplast ATP synthase, slowing proton efflux from the thylakoid lumen resulting in buildup of thylakoid proton motive force (pmf). The resulting acidification of the lumen regulates both light harvesting, via the qE mechanism, and photosynthetic electron transfer through the cytochrome b 6f complex. Here in this paper, we show that the cfq mutant of Arabidopsis, harboring single point mutation in its γ-subunit of the chloroplast ATP synthase, increases the specific activity of the ATP synthase and disables its down-regulation under low CO 2. The increased thylakoid proton conductivity (g H +) in cfq results in decreased pmf and lumen acidification, preventing full activation of qE and more rapid electron transfer through the b6f complex, particularly under low CO 2 and fluctuating light. These conditions favor the accumulation of electrons on the acceptor side of PSI, and result in severe loss of PSI activity. Comparing the current results with previous work on the pgr5 mutant suggests a general mechanism where increased PSI photodamage in both mutants is caused by loss of pmf, rather than inhibition of CEF per se. Overall, our results support a critical role for ATP synthasemore » regulation in maintaining photosynthetic control of electron transfer to prevent photodamage.« less
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [2] ;  [2] ;  [2] ;  [4] ;  [2] ;  [4] ;  [4]
+ Show Author Affiliations
  1. Michigan State Univ., East Lansing, MI (United States). MSU-DOE Plant Research Lab.; Michigan State Univ., East Lansing, MI (United States). Dept. of Chemistry
  2. Michigan State Univ., East Lansing, MI (United States). MSU-DOE Plant Research Lab.
  3. Michigan State Univ., East Lansing, MI (United States). MSU-DOE Plant Research Lab.; Michigan State Univ., East Lansing, MI (United States). Dept. of Cell and Molecular Biology
  4. Michigan State Univ., East Lansing, MI (United States). MSU-DOE Plant Research Lab.; Michigan State Univ., East Lansing, MI (United States). Dept. Biochemistry and Molecular Biology
Publication Date:
Grant/Contract Number:
FG02-91ER20021
Type:
Accepted Manuscript
Journal Name:
Frontiers in Plant Science
Additional Journal Information:
Journal Volume: 8; Journal ID: ISSN 1664-462X
Publisher:
Frontiers Research Foundation
Research Org:
Michigan State Univ., East Lansing, MI (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; ATP synthase; proton motive force; pmf, photoprotection; PSI; PSII
OSTI Identifier:
1368188
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  • Cited by: 3works
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