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The 2.4 A cryo-EM structure of a heptameric light-harvesting 2 complex reveals two carotenoid energy transfer pathways.

ABSTRACT: We report the 2.4 Ångström resolution structure of the light-harvesting 2 (LH2) complex from Marichromatium (Mch.) purpuratum determined by cryogenic electron microscopy. The structure contains a heptameric ring that is unique among all known LH2 structures, explaining the unusual spectroscopic properties of this bacterial antenna complex. We identify two sets of distinct carotenoids in the structure and describe a network of energy transfer pathways from the carotenoids to bacteriochlorophyll a molecules. The geometry imposed by the heptameric ring controls the resonant coupling of the long-wavelength energy absorption band. Together, these details reveal key aspects of the assembly and oligomeric form of purple bacterial LH2 complexes that were previously inaccessible by any technique.

SUBMITTER: Gardiner AT

PROVIDER: S-EPMC7880592 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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The 2.4 Å cryo-EM structure of a heptameric light-harvesting 2 complex reveals two carotenoid energy transfer pathways.

Gardiner Alastair T AT Naydenova Katerina K Castro-Hartmann Pablo P Nguyen-Phan Tu C TC Russo Christopher J CJ Sader Kasim K Hunter C Neil CN Cogdell Richard J RJ Qian Pu P

Science advances 20210212 7

We report the 2.4 Ångström resolution structure of the light-harvesting 2 (LH2) complex from Marichromatium (Mch.) purpuratum determined by cryogenic electron microscopy. The structure contains a heptameric ring that is unique among all known LH2 structures, explaining the unusual spectroscopic properties of this bacterial antenna complex. We identify two sets of distinct carotenoids in the structure and describe a network of energy transfer pathways from the carotenoids to ...[more]

PMID: 33579696

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