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J Biol Chem. 2017 Jan 27;292(4):1396-1403. doi: 10.1074/jbc.M116.753723. Epub 2016 Dec 19.

Twisting a β-Carotene, an Adaptive Trick from Nature for Dissipating Energy during Photoprotection.

Author information

1
From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, F-91198, Gif-sur-Yvette cedex, France, manuel.llansola@cea.fr.
2
the Centre Algatech, Institute of Microbiology, Academy of Sciences of the Czech Republic, Třeboň, 379 81, Czech Republic, and.
3
From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, F-91198, Gif-sur-Yvette cedex, France.
4
the Institute of Physics and Biophysics, Faculty of Science, University of South Bohemia, České Budějovice 370 01, Czech Republic.

Abstract

Cyanobacteria possess a family of one-helix high light-inducible proteins (Hlips) that are homologous to light-harvesting antenna of plants and algae. An Hlip protein, high light-inducible protein D (HliD) purified as a small complex with the Ycf39 protein is evaluated using resonance Raman spectroscopy. We show that the HliD binds two different β-carotenes, each present in two non-equivalent binding pockets with different conformations, having their (0,0) absorption maxima at 489 and 522 nm, respectively. Both populations of β-carotene molecules were in all-trans configuration and the absorption position of the farthest blue-shifted β-carotene was attributed entirely to the polarizability of the environment in its binding pocket. In contrast, the absorption maximum of the red-shifted β-carotene was attributed to two different factors: the polarizability of the environment in its binding pocket and, more importantly, to the conformation of its β-rings. This second β-carotene has highly twisted β-rings adopting a flat conformation, which implies that the effective conjugation length N is extended up to 10.5 modifying the energetic levels. This increase in N will also result in a lower S1 energy state, which may provide a permanent energy dissipation channel. Analysis of the carbonyl stretching region for chlorophyll a excitations indicates that the HliD binds six chlorophyll a molecules in five non-equivalent binding sites, with at least one chlorophyll a presenting a slight distortion to its macrocycle. The binding modes and conformations of HliD-bound pigments are discussed with respect to the known structures of LHCII and CP29.

KEYWORDS:

carotenoid; chlorophyll; cyanobacteria; light-harvesting complex (antenna complex); photosynthesis

PMID:
27994060
PMCID:
PMC5270482
DOI:
10.1074/jbc.M116.753723
[Indexed for MEDLINE]
Free PMC Article

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