Visualizing the chaperone-mediated folding trajectory of the G protein β5 β-propeller

Wang, S.; Sass, M. I.; Kwon, Y.; Ludlam, W. G.; Smith, T. M.; Carter, E. J.; Gladden, N. E.; Riggi, M.; Iwasa, J. H.; Willardson, B. M.; Shen, P. S.

doi:10.1101/2023.05.04.539424

bioRxiv · 10.1101/2023.05.04.539424

Visualizing the chaperone-mediated folding trajectory of the G protein β5 β-propeller

Wang, S.·Sass, M. I.·Kwon, Y.·Ludlam, W. G.·Smith, T. M.·Carter, E. J.·Gladden, N. E.·Riggi, M.·Iwasa, J. H.·Willardson, B. M.·Shen, P. S.

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Abstract

The cytosolic Chaperonin Containing Tailless polypeptide 1 (CCT) complex is an essential protein folding machine with a diverse clientele of substrates, including many proteins with {beta}- propeller domains. Here, we determined structures of CCT in complex with its accessory co chaperone, phosducin-like protein 1 (PhLP1), in the process of folding G{beta}5, a component of Regulator of G protein Signaling (RGS) complexes. Cryo-EM and image processing revealed an ensemble of distinct snapshots that represent the folding trajectory of G{beta}5 from an unfolded molten globule to a fully folded {beta}-propeller. These structures reveal the mechanism by which CCT directs G{beta}5 folding through initiating specific intermolecular contacts that facilitate the sequential folding of individual {beta}-sheets until the propeller closes into its native structure. This work directly visualizes chaperone-mediated protein folding and establishes that CCT directs folding by stabilizing intermediates through interactions with surface residues that permit the hydrophobic core to coalesce into its folded state.

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Wang, S., Sass, M. I., Kwon, Y., Ludlam, W. G., Smith, T. M., Carter, E. J., Gladden, N. E., Riggi, M., Iwasa, J. H., Willardson, B. M., Shen, P. S.. 2023-05-04. Visualizing the chaperone-mediated folding trajectory of the G protein β5 β-propeller. https://doi.org/10.1101/2023.05.04.539424

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