title: Determination of Cell Doubling Times from the Return-on-Investment Time of Photosynthetic Vesicles Based on Atomic Detail Structural Models.
abstract: Cell doubling times of the purple bacterium Rhodobacter sphaeroides during photosynthetic growth are determined experimentally and computationally as a function of illumination. For this purpose, energy conversion processes in an intracytoplasmic membrane vesicle, the chromatophore, are described based on an atomic detail structural model. The cell doubling time and its illumination dependence are computed in terms of the return-on-investment (ROI) time of the chromatophore, determined computationally from the ATP production rate, and the mass ratio of chromatophores in the cell, determined experimentally from whole cell absorbance spectra. The ROI time is defined as the time it takes to produce enough ATP to pay for the construction of another chromatophore. The ROI time of the low light-growth chromatophore is 4.5-2.6 h for a typical illumination range of 10-100 μmol photons m-2s-1, respectively, with corresponding cell doubling times of 8.2-3.9 h. When energy expenditure is considered as a currency, the benefit-to-cost ratio computed for the chromatophore as an energy harvesting device is 2-8 times greater than for photovoltaic and fossil fuel-based energy solutions and the corresponding ROI times are approximately 3-4 orders of magnitude shorter for the chromatophore than for synthetic systems.
authors.affiliation: Department of Molecular Biology and Biotechnology, University of Sheffield , Sheffield S10 2TN, U.K.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hitchcock
authors.affiliation: Department of Molecular Biology and Biotechnology, University of Sheffield , Sheffield S10 2TN, U.K.
authors.forename: C Neil
authors.identifier: 0000-0003-2533-9783
authors.initials: CN
authors.lastname: Hunter
authors.affiliation: Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.|Department of Physics, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Melih
authors.identifier: 0000-0002-6773-6333
authors.initials: M
authors.lastname: Sener
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis; D020130:Bacterial Chromatophores / Q000737:chemistry* / Q000378:metabolism; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D011487:Protein Conformation; D012242:Rhodobacter sphaeroides / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D013997:Time Factors
chemical_list: D045342:Light-Harvesting Protein Complexes; D000255:Adenosine Triphosphate