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Title: Experimental evidence that the membrane-spanning helix of PufX adopts a bent conformation that facilitates dimerisation of the Rhodobacter sphaeroides RC-LH1 complex through N-terminal interactions

Abstract

The PufX polypeptide is an integral component of some photosynthetic bacterial reaction center-light harvesting 1 (RC–LH1) core complexes. Many aspects of the structure of PufX are unresolved, including the conformation of its long membrane-spanning helix and whether C-terminal processing occurs. In the present report, NMR data recorded on the Rhodobacter sphaeroides PufX in a detergent micelle confirmed previous conclusions derived from equivalent data obtained in organic solvent, that the α-helix of PufX adopts a bent conformation that would allow the entire helix to reside in the membrane interior or at its surface. In support of this, it was found through the use of site-directed mutagenesis that increasing the size of a conserved glycine on the inside of the bend in the helix was not tolerated. Possible consequences of this bent helical structure were explored using a series of N-terminal deletions. The N-terminal sequence ADKTIFNDHLN on the cytoplasmic face of the membrane was found to be critical for the formation of dimers of the RC–LH1 complex. It was further shown that the C-terminus of PufX is processed at an early stage in the development of the photosynthetic membrane. A model in which two bent PufX polypeptides stabilise a dimeric RC–LH1 complexmore » is presented, and it is proposed that the N-terminus of PufX from one half of the dimer engages in electrostatic interactions with charged residues on the cytoplasmic surface of the LH1α and β polypeptides on the other half of the dimer.« less

Authors:
; ; ; ; ; ; ; ;
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Photosynthetic Antenna Research Center (PARC)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1065086
DOE Contract Number:  
SC0001035
Resource Type:
Journal Article
Journal Name:
Biochim. Biophys. Acta, Bioenerg.
Additional Journal Information:
Journal Volume: 1807; Related Information: PARC partners with Washington University in St. Louis (lead); University of California, Riverside; University of Glasgow, UK; Los Alamos National Laboratory; University of New Mexico; New Mexico Corsortium; North Carolina State University; Northwestern University; Oak Ridge National Laboratory; University of Pennsylvania; Sandia National Laboratories; University of Sheffield, UK
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; solar (fuels), photosynthesis (natural and artificial), biofuels (including algae and biomass), bio-inspired, charge transport, membrane, synthesis (novel materials), synthesis (self-assembly)

Citation Formats

Ratcliffe, Emma C, Tunnicliffe, Richard B, Ng, Irene W, Adams, Peter G, Qian, Pu, Holden-Dye, Katherine, Jones, Michael R, Williamson, Michael P, and Hunter, C Neil. Experimental evidence that the membrane-spanning helix of PufX adopts a bent conformation that facilitates dimerisation of the Rhodobacter sphaeroides RC-LH1 complex through N-terminal interactions. United States: N. p., Web. doi:10.1016/j.bbabio.2010.10.003.
Ratcliffe, Emma C, Tunnicliffe, Richard B, Ng, Irene W, Adams, Peter G, Qian, Pu, Holden-Dye, Katherine, Jones, Michael R, Williamson, Michael P, & Hunter, C Neil. Experimental evidence that the membrane-spanning helix of PufX adopts a bent conformation that facilitates dimerisation of the Rhodobacter sphaeroides RC-LH1 complex through N-terminal interactions. United States. https://doi.org/10.1016/j.bbabio.2010.10.003
Ratcliffe, Emma C, Tunnicliffe, Richard B, Ng, Irene W, Adams, Peter G, Qian, Pu, Holden-Dye, Katherine, Jones, Michael R, Williamson, Michael P, and Hunter, C Neil. . "Experimental evidence that the membrane-spanning helix of PufX adopts a bent conformation that facilitates dimerisation of the Rhodobacter sphaeroides RC-LH1 complex through N-terminal interactions". United States. https://doi.org/10.1016/j.bbabio.2010.10.003.
@article{osti_1065086,
title = {Experimental evidence that the membrane-spanning helix of PufX adopts a bent conformation that facilitates dimerisation of the Rhodobacter sphaeroides RC-LH1 complex through N-terminal interactions},
author = {Ratcliffe, Emma C and Tunnicliffe, Richard B and Ng, Irene W and Adams, Peter G and Qian, Pu and Holden-Dye, Katherine and Jones, Michael R and Williamson, Michael P and Hunter, C Neil},
abstractNote = {The PufX polypeptide is an integral component of some photosynthetic bacterial reaction center-light harvesting 1 (RC–LH1) core complexes. Many aspects of the structure of PufX are unresolved, including the conformation of its long membrane-spanning helix and whether C-terminal processing occurs. In the present report, NMR data recorded on the Rhodobacter sphaeroides PufX in a detergent micelle confirmed previous conclusions derived from equivalent data obtained in organic solvent, that the α-helix of PufX adopts a bent conformation that would allow the entire helix to reside in the membrane interior or at its surface. In support of this, it was found through the use of site-directed mutagenesis that increasing the size of a conserved glycine on the inside of the bend in the helix was not tolerated. Possible consequences of this bent helical structure were explored using a series of N-terminal deletions. The N-terminal sequence ADKTIFNDHLN on the cytoplasmic face of the membrane was found to be critical for the formation of dimers of the RC–LH1 complex. It was further shown that the C-terminus of PufX is processed at an early stage in the development of the photosynthetic membrane. A model in which two bent PufX polypeptides stabilise a dimeric RC–LH1 complex is presented, and it is proposed that the N-terminus of PufX from one half of the dimer engages in electrostatic interactions with charged residues on the cytoplasmic surface of the LH1α and β polypeptides on the other half of the dimer.},
doi = {10.1016/j.bbabio.2010.10.003},
url = {https://www.osti.gov/biblio/1065086}, journal = {Biochim. Biophys. Acta, Bioenerg.},
number = ,
volume = 1807,
place = {United States},
year = {},
month = {}
}