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Biochim Biophys Acta. 2014 Jun;1837(6):811-24. doi: 10.1016/j.bbabio.2014.01.020. Epub 2014 Feb 7.

Single-molecule in vivo imaging of bacterial respiratory complexes indicates delocalized oxidative phosphorylation.

Author information

1
Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, UK; Department of Physics and Astronomy, University College London, Gower St., London WC1E 6BT, UK.
2
School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK; QB3 University of California, Berkeley CA94720, USA.
3
Institut für Biochemie 79104 Freiburg, Germany.
4
Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, UK.
5
School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK.
6
QB3 University of California, Berkeley CA94720, USA.
7
Biological Physical Sciences Institute (BPSI), University of York, York YO10 5DD, UK. Electronic address: mark.leake@york.ac.uk.

Abstract

Chemiosmotic energy coupling through oxidative phosphorylation (OXPHOS) is crucial to life, requiring coordinated enzymes whose membrane organization and dynamics are poorly understood. We quantitatively explore localization, stoichiometry, and dynamics of key OXPHOS complexes, functionally fluorescent protein-tagged, in Escherichia coli using low-angle fluorescence and superresolution microscopy, applying single-molecule analysis and novel nanoscale co-localization measurements. Mobile 100-200nm membrane domains containing tens to hundreds of complexes are indicated. Central to our results is that domains of different functional OXPHOS complexes do not co-localize, but ubiquinone diffusion in the membrane is rapid and long-range, consistent with a mobile carrier shuttling electrons between islands of different complexes. Our results categorically demonstrate that electron transport and proton circuitry in this model bacterium are spatially delocalized over the cell membrane, in stark contrast to mitochondrial bioenergetic supercomplexes. Different organisms use radically different strategies for OXPHOS membrane organization, likely depending on the stability of their environment.

KEYWORDS:

Co-localization analysis; Cytoplasmic membrane; Fluorescence microscopy; Fluorescent protein; Oxidative phosphorylation; Single-molecule biophysics

PMID:
24513194
DOI:
10.1016/j.bbabio.2014.01.020
[Indexed for MEDLINE]
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