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Title: Overall energy conversion efficiency of a photosynthetic vesicle

The chromatophore of purple bacteria is an intracellular spherical vesicle that exists in numerous copies in the cell and that efficiently converts sunlight into ATP synthesis, operating typically under low light conditions. Building on an atomic-level structural model of a low-light-adapted chromatophore vesicle from Rhodobacter sphaeroides, we investigate the cooperation between more than a hundred protein complexes in the vesicle. The steady-state ATP production rate as a function of incident light intensity is determined after identifying quinol turnover at the cytochrome bc1 complex (cytbc1) as rate limiting and assuming that the quinone/quinol pool of about 900 molecules acts in a quasi-stationary state. For an illumination condition equivalent to 1% of full sunlight, the vesicle exhibits an ATP production rate of 82 ATP molecules/s. The energy conversion efficiency of ATP synthesis at illuminations corresponding to 1%–5% of full sunlight is calculated to be 0.12-0.04, respectively. The vesicle stoichiometry, evolutionarily adapted to the low light intensities in the habitat of purple bacteria, is suboptimal for steady-state ATP turnover for the benefit of protection against over-illumination.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ; ORCiD logo [5]
  1. Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, United States; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, United States
  2. Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, United States; Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, United States
  3. Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, United States
  4. Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
  5. Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, United States; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, United States; Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, United States
Publication Date:
Grant/Contract Number:
SC0001035
Type:
Published Article
Journal Name:
eLife
Additional Journal Information:
Journal Volume: 5; 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; Journal ID: ISSN 2050-084X
Publisher:
eLife Sciences Publications, Ltd.
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) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
solar (fuels), photosynthesis (natural and artificial), biofuels (including algae and biomass), bio-inspired, charge transport, membrane, synthesis (novel materials), synthesis (self-assembly)
OSTI Identifier:
1307791
Alternate Identifier(s):
OSTI ID: 1307792; OSTI ID: 1388788