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bioRxiv · 10.1101/2022.02.25.481955

Cryo-EM structure of the Rhodobaca bogoriensis RC-LH1-PufX dimeric complex at 2.9 angstrom

Semchonok, D. A.·Siponen, M. I.·Toeting, C.·Charras, Q.·Kyrilis, F. L.·Sadian, Y.·Jungas, C.·Kastritis, P. L.
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Abstract

The reaction centre-light harvesting 1 (RC-LH1) complex is essential for converting light into proton motive force in photosynthetic bacteria. RC-LH1 is a monomer in most purple bacteria, but in Rhodobacter species, it is a dimer. Its assembly depends on an accessory polypeptide (PufX) and, ultimately, on photosynthetic growth. To date, knowledge on the RC-LH1-PufX structure, where the dimer has two incomplete C-shaped antenna rings surrounding an RC, is mainly limited to the model organism Rhodobacter sphaeroides. Here we present a cryo-electron microscopy structure at 2.9 [A] from Rhodobaca bogorensis strain LBB1. RCs are surrounded by 30 antennas and incorporate protein Y and PufX. RCs are stably connected by PufX, which self-interacts, electrostatically attracts cytochrome c2 (cyt c2) and forms extensive networks with co-factors. This structure underlines coordinated energy transfer in a combinatorial manner, providing a basis to describe bacterial photosynthesis within a dimeric photosynthetic apparatus.

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Semchonok, D. A., Siponen, M. I., Toeting, C., Charras, Q., Kyrilis, F. L., Sadian, Y., Jungas, C., Kastritis, P. L.. 2022-02-26. Cryo-EM structure of the Rhodobaca bogoriensis RC-LH1-PufX dimeric complex at 2.9 angstrom. https://doi.org/10.1101/2022.02.25.481955

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