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

Gardiner, A. T., Naydenova, K., Castro-Hartmann, P., Nguyen-Phan, C. T., Russo, C. J., Sader, K., Hunter, C. N., Cogdell, R. J. and Qian, P. (2021) The 2.4 Å cryo-EM structure of a heptameric light-harvesting 2 complex reveals two carotenoid energy transfer pathways. Science Advances, 7(7), eabe4650. (doi: 10.1126/sciadv.abe4650) (PMID:33579696) (PMCID:PMC7880592)

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.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Nguyen Phan, Cam Tu and Cogdell, Professor Richard and Gardiner, Dr Alastair
• Authors: Gardiner, A. T., Naydenova, K., Castro-Hartmann, P., Nguyen-Phan, C. T., Russo, C. J., Sader, K., Hunter, C. N., Cogdell, R. J., and Qian, P.
• College/School: College of Medical Veterinary and Life Sciences > School of Infection & Immunity; College of Medical Veterinary and Life Sciences > School of Molecular Biosciences
• Journal Name: Science Advances
• Publisher: American Association for the Advancement of Science
• ISSN: 2375-2548
• ISSN (Online): 2375-2548
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Science Advances 7(7):eabe4650
• Publisher Policy: Reproduced under a Creative Commons licence