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Title: The Chloroplast Tat Pathway Transports Substrates in the Dark

Abstract

Photosynthetic electron transport pumps protons into the thylakoid lumen, creating an electrochemical potential called the protonmotive force (PMF). The energy of the thylakoid PMF is utilized by such machinery as the chloroplast F0F1-ATPase as well as the chloroplast Tat (cpTat) pathway (a protein transporter) to do work. The bulk phase thylakoid PMF decays rapidly after the termination of actinic illumination, and it has been well established via potentiometric measurements that there is no detectable electrical or chemical potential in the thylakoid after a brief time in the dark. Yet, we report herein that cpTat transport can occur for long periods in the dark. We show that the thylakoid PMF is actually present long after actinic illumination of the thylakoids ceases and that this energy is present in physiologically useful quantities. Consistent with previous studies, the dark-persisting thylakoid potential is not detectable by established indicators. In conclusion, we propose that cpTat transport in the dark is dependent on a pool of protons in the thylakoid held out of equilibrium with those in the bulk aqueous phase.

Authors:
 [1];  [2]
  1. Univ. of California, Davis, CA (United States); Univ. of Manchester, Manchester (United Kingdom)
  2. Univ. of California, Davis, CA (United States)
Publication Date:
Research Org.:
Univ. of California, Davis, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
OSTI Identifier:
1490447
Grant/Contract Number:  
FG02-03ER15405
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Biological Chemistry
Additional Journal Information:
Journal Volume: 283; Journal Issue: 14; Journal ID: ISSN 0021-9258
Publisher:
American Society for Biochemistry and Molecular Biology
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES

Citation Formats

Braun, Nikolai A., and Theg, Steven M. The Chloroplast Tat Pathway Transports Substrates in the Dark. United States: N. p., 2008. Web. doi:10.1074/jbc.M708948200.
Braun, Nikolai A., & Theg, Steven M. The Chloroplast Tat Pathway Transports Substrates in the Dark. United States. doi:10.1074/jbc.M708948200.
Braun, Nikolai A., and Theg, Steven M. Wed . "The Chloroplast Tat Pathway Transports Substrates in the Dark". United States. doi:10.1074/jbc.M708948200. https://www.osti.gov/servlets/purl/1490447.
@article{osti_1490447,
title = {The Chloroplast Tat Pathway Transports Substrates in the Dark},
author = {Braun, Nikolai A. and Theg, Steven M.},
abstractNote = {Photosynthetic electron transport pumps protons into the thylakoid lumen, creating an electrochemical potential called the protonmotive force (PMF). The energy of the thylakoid PMF is utilized by such machinery as the chloroplast F0F1-ATPase as well as the chloroplast Tat (cpTat) pathway (a protein transporter) to do work. The bulk phase thylakoid PMF decays rapidly after the termination of actinic illumination, and it has been well established via potentiometric measurements that there is no detectable electrical or chemical potential in the thylakoid after a brief time in the dark. Yet, we report herein that cpTat transport can occur for long periods in the dark. We show that the thylakoid PMF is actually present long after actinic illumination of the thylakoids ceases and that this energy is present in physiologically useful quantities. Consistent with previous studies, the dark-persisting thylakoid potential is not detectable by established indicators. In conclusion, we propose that cpTat transport in the dark is dependent on a pool of protons in the thylakoid held out of equilibrium with those in the bulk aqueous phase.},
doi = {10.1074/jbc.M708948200},
journal = {Journal of Biological Chemistry},
number = 14,
volume = 283,
place = {United States},
year = {2008},
month = {1}
}

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Cited by: 11 works
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Works referenced in this record:

Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4
journal, August 1970