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Title: Adaptation of Rhodopseudomonas acidophila strain 7050 to growth at different light intensities: what are the benefits to changing the type of LH2?

Abstract

Femto-second time resolved absorption has been used to investigate how the energy transfer properties in the membranes of high-light and low-light adapted cells change as the composition of the LH2 complexes varies.

Authors:
ORCiD logo [1]; ORCiD logo [2];  [1]
  1. Institute of Molecular, Cellular and Systems Biology, University of Glasgow, University Avenue, Glasgow
  2. Photosynthetic Antenna Research Center, Washington University in St Louis, MO 63130, USA
Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1417678
Grant/Contract Number:
SC 0001035
Resource Type:
Journal Article: Published Article
Journal Name:
Faraday Discussions
Additional Journal Information:
Related Information: CHORUS Timestamp: 2018-01-22 06:13:56; Journal ID: ISSN 1359-6640
Publisher:
Royal Society of Chemistry (RSC)
Country of Publication:
United Kingdom
Language:
English

Citation Formats

Gardiner, A. T., Niedzwiedzki, D. M., and Cogdell, R. J.. Adaptation of Rhodopseudomonas acidophila strain 7050 to growth at different light intensities: what are the benefits to changing the type of LH2?. United Kingdom: N. p., 2018. Web. doi:10.1039/C7FD00191F.
Gardiner, A. T., Niedzwiedzki, D. M., & Cogdell, R. J.. Adaptation of Rhodopseudomonas acidophila strain 7050 to growth at different light intensities: what are the benefits to changing the type of LH2?. United Kingdom. doi:10.1039/C7FD00191F.
Gardiner, A. T., Niedzwiedzki, D. M., and Cogdell, R. J.. 2018. "Adaptation of Rhodopseudomonas acidophila strain 7050 to growth at different light intensities: what are the benefits to changing the type of LH2?". United Kingdom. doi:10.1039/C7FD00191F.
@article{osti_1417678,
title = {Adaptation of Rhodopseudomonas acidophila strain 7050 to growth at different light intensities: what are the benefits to changing the type of LH2?},
author = {Gardiner, A. T. and Niedzwiedzki, D. M. and Cogdell, R. J.},
abstractNote = {Femto-second time resolved absorption has been used to investigate how the energy transfer properties in the membranes of high-light and low-light adapted cells change as the composition of the LH2 complexes varies.},
doi = {10.1039/C7FD00191F},
journal = {Faraday Discussions},
number = ,
volume = ,
place = {United Kingdom},
year = 2018,
month = 1
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1039/C7FD00191F

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  • One- and two-color pump/probe femtosecond and hole-burning data are reported for the isolated B800-850 (LH2) antenna complex of Rhodopseudomonas acidophila (strain 10050). The two-color profiles are interpretable in terms of essentially monophasic B800{yields}B850 energy transfer with kinetics ranging from 1.6 to 1.1 ps between 19 and 130 K for excitation at or to the red of the B800 absorption maximum. The B800 zero-phonon hole profiles obtained at 4.2 K with burn frequencies located near or to the red of this maximum yielded a transfer time of 1.8 ps. B800 hole-burning data (4.2 K) are also reported for chromatophores at ambientmore » pressure and pressures of 270 and 375 MPa. At ambient pressure the B800-B850 energy gap is 950 cm{sup -1}, while at 270 and 375 MPa it is close to 1000 and 1050 cm{sup -1}, respectively. However, no dependence of the B800{yields}B850 transfer time on pressure was observed. The resilience of the transfer rate to pressure-induced changes in the energy gap and the weak temperature dependence of the rate are consistent with the model that has the spectral overlap (of Foerster theory) provided by the B800 fluorescence origin band and weak vibronic absorption bands of B850. However, both the time domain and hole-burning data establish that there is an additional relaxation channel for B800, which is observed when excitation is located to the blue of the B800 absorption maximum. 40 refs., 11 figs., 6 tabs.« less
  • The results of 4.2 K absorption and hole-burning experiments on the B850 absorption band of isolated LH2 antenna complexes from Rhodopseudomonas acidophila are presented for samples that exhibited a B850 absorption band of sufficient narrowness that allows direct observation of the lowest exciton level of the B850 ring of dimers as a weak but distinct shoulder at the red edge of the B850 band. The diagonal and/or off-diagonal energy disorder within the B850 ring is proven to be important in understanding B870 and the electronic structure of B850. Data pertaining to the pure dephasing of the B870 exciton level aremore » presented and are interpreted in terms of scattering due to imperfections in the B850 ring. 24 refs., 6 figs.« less
  • Energy transfer processes in photosynthetic light harvesting 2 (LH2) complexes isolated from purple bacterium Rhodopseudomonas palustris grown at different light intensities were studied by ground state and transient absorption spectroscopy. The decomposition of ground state absorption spectra shows contributions from B800 and B850 bacteriochlorophyll (BChl) a rings, the latter component splitting into a low energy and a high energy band in samples grown under low light (LL) conditions. A spectral analysis reveals strong inhomogeneity of the B850 excitons in the LL samples that is well reproduced by an exponential-type distribution. Transient spectra show a bleach of both the low energymore » and high energy bands, together with the respective blue-shifted exciton-to-biexciton transitions. The different spectral evolutions were analyzed by a global fitting procedure. Energy transfer from B800 to B850 occurs in a mono-exponential process and the rate of this process is only slightly reduced in LL compared to high light samples. In LL samples, spectral relaxation of the B850 exciton follows strongly nonexponential kinetics that can be described by a reduction of the bleach of the high energy excitonic component and a red-shift of the low energetic one. We explain these spectral changes by picosecond exciton relaxation caused by a small coupling parameter of the excitonic splitting of the BChl a molecules to the surrounding bath. The splitting of exciton energy into two excitonic bands in LL complex is most probably caused by heterogenous composition of LH2 apoproteins that gives some of the BChls in the B850 ring B820-like site energies, and causes a disorder in LH2 structure.« less
  • The slow strain rate testing (SSRT) technique was used to investigate the stress corrosion cracking (SCC) behavior of aluminum alloy Al 7050 in different tempers in various electrolytes at the free-corrosion potential. Smooth tensile specimens were strained dynamically in the short transverse direction under permanent immersion conditions. Strain rates were from 5 {times} 10{sup {minus}8}/s to 1 {times} 10{sup {minus}4}/s. Using substitute ocean water, Al 7050 was found sensitive and immune to environmentally assisted cracking in the peak-aged temper T651 and in the over-aged temper T7351, respectively. In the less-over-aged heat treatment T7651, fracture energy data revealed a large scatter.more » An aqueous solution of 0.5 M sodium perchlorate was not conducive to environmentally assisted cracking. SSRT performed in an aqueous solution of 0.1 M sodium chloride + 0.05 M sodium sulfate + 0.05 M sodium nitrate + 0.01 M sodium bicarbonate at pH 3.5 indicated SCC susceptibility for Al 7050-T651. The latter electrolyte did not promote SCC with the alloy in the heat treatments T7651 and T7351. Scatter was observed in the fracture energy data of Al 7050-T7351 specimens dynamically strained in the mixed salt solution. Deterioration was attributed to pitting attack, as supported by fractography.« less