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Title: The Chloroplast Tat Pathway Utilizes the Transmembrane Electric Potential as an Energy Source

Abstract

Here, the thylakoid membrane, located inside the chloroplast, requires proteins transported across it for plastid biogenesis and functional photosynthetic electron transport. The chloroplast Tat translocator found on thylakoids transports proteins from the plastid stroma to the thylakoid lumen. Previous studies have shown that the chloroplast Tat pathway is independent of NTP hydrolysis as an energy source and instead depends on the thylakoid transmembrane proton gradient to power protein translocation. Because of its localization on the same membrane as the proton motive force-dependent F 0F 1 ATPase, we believed that the chloroplast Tat pathway also made use of the thylakoid electric potential for transporting substrates. By adjusting the rate of photosynthetic proton pumping and by utilizing ionophores, we show that the chloroplast Tat pathway can also utilize the transmembrane electric potential for protein transport. Our findings indicate that the chloroplast Tat pathway is likely dependent on the total protonmotive force (PMF) as an energy source. As a protonmotive-dependent device, certain predictions can be made about structural features expected to be found in the Tat translocon, specifically, the presence of a proton well, a device in the membrane that converts electrical potential into chemical potential.

Authors:
 [1];  [1];  [1]
  1. Univ. of California, Davis, CA (United States). Dept. of Plant Biology
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:
1490449
Grant/Contract Number:  
FG02-03ER15405
Resource Type:
Accepted Manuscript
Journal Name:
Biophysical Journal
Additional Journal Information:
Journal Volume: 93; Journal Issue: 6; Journal ID: ISSN 0006-3495
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES

Citation Formats

Braun, Nikolai A., Davis, Andrew W., and Theg, Steven M. The Chloroplast Tat Pathway Utilizes the Transmembrane Electric Potential as an Energy Source. United States: N. p., 2009. Web. doi:10.1529/biophysj.106.098731.
Braun, Nikolai A., Davis, Andrew W., & Theg, Steven M. The Chloroplast Tat Pathway Utilizes the Transmembrane Electric Potential as an Energy Source. United States. doi:10.1529/biophysj.106.098731.
Braun, Nikolai A., Davis, Andrew W., and Theg, Steven M. Tue . "The Chloroplast Tat Pathway Utilizes the Transmembrane Electric Potential as an Energy Source". United States. doi:10.1529/biophysj.106.098731. https://www.osti.gov/servlets/purl/1490449.
@article{osti_1490449,
title = {The Chloroplast Tat Pathway Utilizes the Transmembrane Electric Potential as an Energy Source},
author = {Braun, Nikolai A. and Davis, Andrew W. and Theg, Steven M.},
abstractNote = {Here, the thylakoid membrane, located inside the chloroplast, requires proteins transported across it for plastid biogenesis and functional photosynthetic electron transport. The chloroplast Tat translocator found on thylakoids transports proteins from the plastid stroma to the thylakoid lumen. Previous studies have shown that the chloroplast Tat pathway is independent of NTP hydrolysis as an energy source and instead depends on the thylakoid transmembrane proton gradient to power protein translocation. Because of its localization on the same membrane as the proton motive force-dependent F0F1 ATPase, we believed that the chloroplast Tat pathway also made use of the thylakoid electric potential for transporting substrates. By adjusting the rate of photosynthetic proton pumping and by utilizing ionophores, we show that the chloroplast Tat pathway can also utilize the transmembrane electric potential for protein transport. Our findings indicate that the chloroplast Tat pathway is likely dependent on the total protonmotive force (PMF) as an energy source. As a protonmotive-dependent device, certain predictions can be made about structural features expected to be found in the Tat translocon, specifically, the presence of a proton well, a device in the membrane that converts electrical potential into chemical potential.},
doi = {10.1529/biophysj.106.098731},
journal = {Biophysical Journal},
number = 6,
volume = 93,
place = {United States},
year = {2009},
month = {1}
}

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