Publication Abstracts

Mielke et al. 2013

Mielke, S.P., N.Y. Kiang, R.E. Blankenship, and D. Mauzerall, 2013: Photosystem trap energies and spectrally-dependent energy-storage efficiencies in the Chl d-utilizing cyanobacterium, Acaryochloris marina. Biochim. Biophys. Acta Bioenerg., 1827, 255-265, doi:10.1016/j.bbabio.2012.11.002.

Acaryochloris marina is the only species known to utilize chlorophyll (Chl) d as a principal photopigment. The peak absorption wavelength of Chl d is redshifted — 40 nm in vivo relative to Chl a, enabling this cyanobacterium to perform oxygenic phototrophy in niche environments enhanced in far-red light. We present measurements of the in vivo energy-storage (E-S) efficiency of photosynthesis in A. marina, obtained using pulsed photoacoustics (PA) over a 90-nm range of excitation wavelengths in the red and far-red. Together with modeling results, these measurements provide the first direct observation of the trap energies of PSI and PSII, and also the photosystem-specific contributions to the total E-S efficiency. We find the maximum observed efficiency in A. marina (40±1% at 735 nm) is higher than in the Chl a cyanobacterium Synechococcus leopoliensis (35±1% at 690 nm). The efficiency at peak absorption wavelength is also higher in A. marina (36±1% at 710 nm vs. 3± 1% at 670 nm). In both species, the trap efficiencies are — 40% (PSI) and — 30% (PSII). The PSI trap in A. marina is found to lie at 740±5 nm, in agreement with the value inferred from spectroscopic methods. The best fit of the model to the PA data identifies the PSII trap at 723±3 nm, supporting the view that the primary electron-donor is Chl d, probably at the accessory (ChlD1) site. These results demonstrate that the E-S efficiency in A. marina is not thermodynamically limited, suggesting that oxygenic photosynthesis is viable in even redder light environments.

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BibTeX Citation

@article{mi00910q,
  author={Mielke, S. P. and Kiang, N. Y. and Blankenship, R. E. and Mauzerall, D.},
  title={Photosystem trap energies and spectrally-dependent energy-storage efficiencies in the Chl d-utilizing cyanobacterium, Acaryochloris marina},
  year={2013},
  journal={Biochim. Biophys. Acta Bioenerg.},
  volume={1827},
  pages={255--265},
  doi={10.1016/j.bbabio.2012.11.002},
}

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RIS Citation

TY  - JOUR
ID  - mi00910q
AU  - Mielke, S. P.
AU  - Kiang, N. Y.
AU  - Blankenship, R. E.
AU  - Mauzerall, D.
PY  - 2013
TI  - Photosystem trap energies and spectrally-dependent energy-storage efficiencies in the Chl d-utilizing cyanobacterium, Acaryochloris marina
JA  - Biochim. Biophys. Acta Bioenerg.
VL  - 1827
SP  - 255
EP  - 265
DO  - 10.1016/j.bbabio.2012.11.002
ER  -

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