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

Abstract

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]
  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:
Research Org.:
Michigan State Univ., East Lansing, MI (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1368188
Grant/Contract Number:  
FG02-91ER20021
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Frontiers in Plant Science
Additional Journal Information:
Journal Volume: 8; Journal ID: ISSN 1664-462X
Publisher:
Frontiers Research Foundation
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; ATP synthase; proton motive force; pmf, photoprotection; PSI; PSII

Citation Formats

Kanazawa, Atsuko, Ostendorf, Elisabeth, Kohzuma, Kaori, Hoh, Donghee, Strand, Deserah D., Sato-Cruz, Mio, Savage, Linda, Cruz, Jeffrey A., Fisher, Nicholas, Froehlich, John E., and Kramer, David M. Chloroplast ATP Synthase Modulation of the Thylakoid Proton Motive Force: Implications for Photosystem I and Photosystem II Photoprotection. United States: N. p., 2017. Web. doi:10.3389/fpls.2017.00719.
Kanazawa, Atsuko, Ostendorf, Elisabeth, Kohzuma, Kaori, Hoh, Donghee, Strand, Deserah D., Sato-Cruz, Mio, Savage, Linda, Cruz, Jeffrey A., Fisher, Nicholas, Froehlich, John E., & Kramer, David M. Chloroplast ATP Synthase Modulation of the Thylakoid Proton Motive Force: Implications for Photosystem I and Photosystem II Photoprotection. United States. doi:10.3389/fpls.2017.00719.
Kanazawa, Atsuko, Ostendorf, Elisabeth, Kohzuma, Kaori, Hoh, Donghee, Strand, Deserah D., Sato-Cruz, Mio, Savage, Linda, Cruz, Jeffrey A., Fisher, Nicholas, Froehlich, John E., and Kramer, David M. Wed . "Chloroplast ATP Synthase Modulation of the Thylakoid Proton Motive Force: Implications for Photosystem I and Photosystem II Photoprotection". United States. doi:10.3389/fpls.2017.00719. https://www.osti.gov/servlets/purl/1368188.
@article{osti_1368188,
title = {Chloroplast ATP Synthase Modulation of the Thylakoid Proton Motive Force: Implications for Photosystem I and Photosystem II Photoprotection},
author = {Kanazawa, Atsuko and Ostendorf, Elisabeth and Kohzuma, Kaori and Hoh, Donghee and Strand, Deserah D. and Sato-Cruz, Mio and Savage, Linda and Cruz, Jeffrey A. and Fisher, Nicholas and Froehlich, John E. and Kramer, David M.},
abstractNote = {In wild type plants, decreasing CO2 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 b6f 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 CO2. The increased thylakoid proton conductivity (gH+) 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 CO2 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 synthase regulation in maintaining photosynthetic control of electron transfer to prevent photodamage.},
doi = {10.3389/fpls.2017.00719},
journal = {Frontiers in Plant Science},
number = ,
volume = 8,
place = {United States},
year = {Wed May 03 00:00:00 EDT 2017},
month = {Wed May 03 00:00:00 EDT 2017}
}

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