In situ high-resolution structure of the baseplate antenna complex in Chlorobaculum tepidum

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Jakob Toudahl Nielsen, Natalia V. Kulminskaya, Morten Bjerring, Juha M Linnanto, Margus Rätsep, Marie Østergaard Pedersen, Petar H. Lambrev, Márta Dorogi, Győző Garab, Karen Thomsen, Caroline Jegerschöld, Niels-Ulrik Frigaard, Martin Lindahl, Niels Chr. Nielsen

Photosynthetic antenna systems enable organisms harvesting light and transfer the energy to the photosynthetic reaction centre, where the conversion to chemical energy takes place. One of the most complex antenna systems, the chlorosome, found in the photosynthetic green sulfur bacterium Chlorobaculum (Cba.) tepidum contains a baseplate, which is a scaffolding super-structure, formed by the protein CsmA and bacteriochlorophyll a. Here we present the first high-resolution structure of the CsmA baseplate using intact fully functional, light-harvesting organelles from Cba. tepidum, following a hybrid approach combining five complementary methods: solid-state NMR spectroscopy, cryo-electron microscopy, isotropic and anisotropic circular dichroism and linear dichroism. The structure calculation was facilitated through development of new software, GASyCS for efficient geometry optimization of highly symmetric oligomeric structures. We show that the baseplate is composed of rods of repeated dimers of the strongly amphipathic CsmA with pigments sandwiched within the dimer at the hydrophobic side of the helix.

Original languageEnglish
Article number12454
JournalNature Communications
Volume7
Number of pages12
ISSN2041-1723
DOIs
Publication statusPublished - 2016

    Research areas

  • Journal Article

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