Engineering of B800 bacteriochlorophyll binding site specificity in the Rhodobacter sphaeroides LH2 antenna

David J.K. Swainsbury, Kaitlyn M. Faries, Dariusz M. Niedzwiedzki, Elizabeth C. Martin, Adam J. Flinders, Daniel P. Canniffe, Gaozhong Shen, Donald Ashley Bryant, Christine Kirmaier, Dewey Holten, C. Neil Hunter

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Abstract

The light-harvesting 2 complex (LH2) of the purple phototrophic bacterium Rhodobacter sphaeroides is a highly efficient, light-harvesting antenna that allows growth under a wide-range of light intensities. In order to expand the spectral range of this antenna complex, we first used a series of competition assays to measure the capacity of the non-native pigments 3-acetyl chlorophyll (Chl) a, Chl d, Chl f or bacteriochlorophyll (BChl) b to replace native BChl a in the B800 binding site of LH2. We then adjusted the B800 site and systematically assessed the binding of non-native pigments. We find that Arg −10 of the LH2 β polypeptide plays a crucial role in binding specificity, by providing a hydrogen-bond to the 3-acetyl group of native and non-native pigments. Reconstituted LH2 complexes harbouring the series of (B)Chls were examined by transient absorption and steady-state fluorescence spectroscopies. Although slowed 10-fold to ~6 ps, energy transfer from Chl a to B850 BChl a remained highly efficient. We measured faster energy-transfer time constants for Chl d (3.5 ps) and Chl f (2.7 ps), which have red-shifted absorption maxima compared to Chl a. BChl b, red-shifted from the native BChl a, gave extremely rapid (≤0.1 ps) transfer. These results show that modified LH2 complexes, combined with engineered (B)Chl biosynthesis pathways in vivo, have potential for retaining high efficiency whilst acquiring increased spectral range.

Original languageEnglish (US)
Pages (from-to)209-223
Number of pages15
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1860
Issue number3
DOIs
StatePublished - Mar 1 2019

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Light-Harvesting Protein Complexes
Bacteriochlorophylls
Rhodobacter sphaeroides
Binding Sites
Antennas
Light
Pigments
Energy Transfer
Energy transfer
Proteobacteria
Fluorescence Spectrometry
Biosynthesis
Fluorescence spectroscopy
Chlorophyll
Hydrogen
Assays
Hydrogen bonds
Peptides

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Cell Biology

Cite this

Swainsbury, D. J. K., Faries, K. M., Niedzwiedzki, D. M., Martin, E. C., Flinders, A. J., Canniffe, D. P., ... Hunter, C. N. (2019). Engineering of B800 bacteriochlorophyll binding site specificity in the Rhodobacter sphaeroides LH2 antenna. Biochimica et Biophysica Acta - Bioenergetics, 1860(3), 209-223. https://doi.org/10.1016/j.bbabio.2018.11.008
Swainsbury, David J.K. ; Faries, Kaitlyn M. ; Niedzwiedzki, Dariusz M. ; Martin, Elizabeth C. ; Flinders, Adam J. ; Canniffe, Daniel P. ; Shen, Gaozhong ; Bryant, Donald Ashley ; Kirmaier, Christine ; Holten, Dewey ; Hunter, C. Neil. / Engineering of B800 bacteriochlorophyll binding site specificity in the Rhodobacter sphaeroides LH2 antenna. In: Biochimica et Biophysica Acta - Bioenergetics. 2019 ; Vol. 1860, No. 3. pp. 209-223.
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Swainsbury, DJK, Faries, KM, Niedzwiedzki, DM, Martin, EC, Flinders, AJ, Canniffe, DP, Shen, G, Bryant, DA, Kirmaier, C, Holten, D & Hunter, CN 2019, 'Engineering of B800 bacteriochlorophyll binding site specificity in the Rhodobacter sphaeroides LH2 antenna', Biochimica et Biophysica Acta - Bioenergetics, vol. 1860, no. 3, pp. 209-223. https://doi.org/10.1016/j.bbabio.2018.11.008

Engineering of B800 bacteriochlorophyll binding site specificity in the Rhodobacter sphaeroides LH2 antenna. / Swainsbury, David J.K.; Faries, Kaitlyn M.; Niedzwiedzki, Dariusz M.; Martin, Elizabeth C.; Flinders, Adam J.; Canniffe, Daniel P.; Shen, Gaozhong; Bryant, Donald Ashley; Kirmaier, Christine; Holten, Dewey; Hunter, C. Neil.

In: Biochimica et Biophysica Acta - Bioenergetics, Vol. 1860, No. 3, 01.03.2019, p. 209-223.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Engineering of B800 bacteriochlorophyll binding site specificity in the Rhodobacter sphaeroides LH2 antenna

AU - Swainsbury, David J.K.

AU - Faries, Kaitlyn M.

AU - Niedzwiedzki, Dariusz M.

AU - Martin, Elizabeth C.

AU - Flinders, Adam J.

AU - Canniffe, Daniel P.

AU - Shen, Gaozhong

AU - Bryant, Donald Ashley

AU - Kirmaier, Christine

AU - Holten, Dewey

AU - Hunter, C. Neil

PY - 2019/3/1

Y1 - 2019/3/1

N2 - The light-harvesting 2 complex (LH2) of the purple phototrophic bacterium Rhodobacter sphaeroides is a highly efficient, light-harvesting antenna that allows growth under a wide-range of light intensities. In order to expand the spectral range of this antenna complex, we first used a series of competition assays to measure the capacity of the non-native pigments 3-acetyl chlorophyll (Chl) a, Chl d, Chl f or bacteriochlorophyll (BChl) b to replace native BChl a in the B800 binding site of LH2. We then adjusted the B800 site and systematically assessed the binding of non-native pigments. We find that Arg −10 of the LH2 β polypeptide plays a crucial role in binding specificity, by providing a hydrogen-bond to the 3-acetyl group of native and non-native pigments. Reconstituted LH2 complexes harbouring the series of (B)Chls were examined by transient absorption and steady-state fluorescence spectroscopies. Although slowed 10-fold to ~6 ps, energy transfer from Chl a to B850 BChl a remained highly efficient. We measured faster energy-transfer time constants for Chl d (3.5 ps) and Chl f (2.7 ps), which have red-shifted absorption maxima compared to Chl a. BChl b, red-shifted from the native BChl a, gave extremely rapid (≤0.1 ps) transfer. These results show that modified LH2 complexes, combined with engineered (B)Chl biosynthesis pathways in vivo, have potential for retaining high efficiency whilst acquiring increased spectral range.

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JO - Biochimica et Biophysica Acta - Bioenergetics

JF - Biochimica et Biophysica Acta - Bioenergetics

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