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Efficiency of light harvesting in a photosynthetic bacterium adapted to different levels of light

Timpmann, Kõu ; Chenchiliyan, Manoop LU ; Jalviste, Erko ; Timney, John A. ; Hunter, C. Neil and Freiberg, Arvi (2014) In Biochimica et Biophysica Acta - Bioenergetics 1837(10). p.1835-1846
Abstract

In this study, we use the photosynthetic purple bacterium Rhodobacter sphaeroides to find out how the acclimation of photosynthetic apparatus to growth conditions influences the rates of energy migration toward the reaction center traps and the efficiency of charge separation at the reaction centers. To answer these questions we measured the spectral and picosecond kinetic fluorescence responses as a function of excitation intensity in membranes prepared from cells grown under different illumination conditions. A kinetic model analysis yielded the microscopic rate constants that characterize the energy transfer and trapping inside the photosynthetic unit as well as the dependence of exciton trapping efficiency on the ratio of the... (More)

In this study, we use the photosynthetic purple bacterium Rhodobacter sphaeroides to find out how the acclimation of photosynthetic apparatus to growth conditions influences the rates of energy migration toward the reaction center traps and the efficiency of charge separation at the reaction centers. To answer these questions we measured the spectral and picosecond kinetic fluorescence responses as a function of excitation intensity in membranes prepared from cells grown under different illumination conditions. A kinetic model analysis yielded the microscopic rate constants that characterize the energy transfer and trapping inside the photosynthetic unit as well as the dependence of exciton trapping efficiency on the ratio of the peripheral LH2 and core LH1 antenna complexes, and on the wavelength of the excitation light. A high quantum efficiency of trapping over 80% was observed in most cases, which decreased toward shorter excitation wavelengths within the near infrared absorption band. At a fixed excitation wavelength the efficiency declines with the LH2/LH1 ratio. From the perspective of the ecological habitat of the bacteria the higher population of peripheral antenna facilitates growth under dim light even though the energy trapping is slower in low light adapted membranes. The similar values for the trapping efficiencies in all samples imply a robust photosynthetic apparatus that functions effectively at a variety of light intensities.

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author
; ; ; ; and
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Exciton, Light harvesting, Optical spectroscopy, Photosynthesis, Photosynthetic unit, Picosecond excitation energy transfer
in
Biochimica et Biophysica Acta - Bioenergetics
volume
1837
issue
10
pages
12 pages
publisher
Elsevier
external identifiers
  • scopus:84906031560
  • pmid:24984074
ISSN
0005-2728
DOI
10.1016/j.bbabio.2014.06.007
language
English
LU publication?
no
id
0f5f26ba-fd35-4aae-be4d-6264e23eee11
date added to LUP
2023-06-16 10:43:12
date last changed
2024-04-05 19:04:34
@article{0f5f26ba-fd35-4aae-be4d-6264e23eee11,
  abstract     = {{<p>In this study, we use the photosynthetic purple bacterium Rhodobacter sphaeroides to find out how the acclimation of photosynthetic apparatus to growth conditions influences the rates of energy migration toward the reaction center traps and the efficiency of charge separation at the reaction centers. To answer these questions we measured the spectral and picosecond kinetic fluorescence responses as a function of excitation intensity in membranes prepared from cells grown under different illumination conditions. A kinetic model analysis yielded the microscopic rate constants that characterize the energy transfer and trapping inside the photosynthetic unit as well as the dependence of exciton trapping efficiency on the ratio of the peripheral LH2 and core LH1 antenna complexes, and on the wavelength of the excitation light. A high quantum efficiency of trapping over 80% was observed in most cases, which decreased toward shorter excitation wavelengths within the near infrared absorption band. At a fixed excitation wavelength the efficiency declines with the LH2/LH1 ratio. From the perspective of the ecological habitat of the bacteria the higher population of peripheral antenna facilitates growth under dim light even though the energy trapping is slower in low light adapted membranes. The similar values for the trapping efficiencies in all samples imply a robust photosynthetic apparatus that functions effectively at a variety of light intensities.</p>}},
  author       = {{Timpmann, Kõu and Chenchiliyan, Manoop and Jalviste, Erko and Timney, John A. and Hunter, C. Neil and Freiberg, Arvi}},
  issn         = {{0005-2728}},
  keywords     = {{Exciton; Light harvesting; Optical spectroscopy; Photosynthesis; Photosynthetic unit; Picosecond excitation energy transfer}},
  language     = {{eng}},
  number       = {{10}},
  pages        = {{1835--1846}},
  publisher    = {{Elsevier}},
  series       = {{Biochimica et Biophysica Acta - Bioenergetics}},
  title        = {{Efficiency of light harvesting in a photosynthetic bacterium adapted to different levels of light}},
  url          = {{http://dx.doi.org/10.1016/j.bbabio.2014.06.007}},
  doi          = {{10.1016/j.bbabio.2014.06.007}},
  volume       = {{1837}},
  year         = {{2014}},
}