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bioRxiv · 10.1101/2023.07.05.547776

Molecular insights into atypical modes of beta-arrestin interaction with seven transmembrane receptors

Maharana, J.·Sano, F. K.·Sarma, P.·Yadav, M. K.·Duan, L.·Stepniewski, T. M.·Chaturvedi, M.·Ranjan, A.·Singh, V.·Saha, S.·Mahajan, G.·Chami, M.·Shihoya, W.·Selent, J.·Chung, K. Y.·Banerjee, R.·Nureki, O.·Shukla, A. K.
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Abstract

{beta}-arrestins are multifunctional proteins that are critically involved in regulating spatio-temporal aspects of GPCR signaling. The interaction of {beta}-arrestins with GPCRs is typically conceptualized in terms of receptor activation and phosphorylation primarily in the carboxyl-terminus. Interestingly however, there are several GPCRs that harbor majority of phosphorylation sites in their 3rd intracellular loop (ICL3) instead of carboxyl-terminus but still robustly engage {beta}-arrestins. Moreover, there are several 7TMRs that are now characterized as intrinsically-biased, {beta}-arrestin-coupled receptors (ACRs) due to lack of functional G-protein-coupling but robust {beta}-arrestin binding leading to functional outcomes. The molecular basis of {beta}-arrestin interaction and activation upon binding to these types of 7TMRs is currently elusive, and it represents a major knowledge gap in our current understanding of this signaling system. Here, we present seven cryo-EM structures of {beta}-arrestins in basal state, activated by the muscarinic M2 receptor (M2R) through its ICL3, and a {beta}-arrestin-coupled receptor known as decoy D6 receptor (D6R). These structural snapshots combined with biochemical, cellular, and biophysical experiments including HDX-MS and MD simulation provide novel insights into the ability of {beta}-arrestins to preferentially select specific phosphorylation patterns in the receptors, and also illuminate the structural diversity in 7TMR-{beta}-arrestin interaction. Surprisingly, we also observe that the carboxyl-terminus of {beta}-arrestin2 but not {beta}-arrestin1 undergoes structural transition from a {beta}-strand to -helix upon activation by D6R, which may preclude the core-interaction with the activated receptor. Taken together, our study elucidates previously unappreciated aspects of 7TMR-{beta}-arrestin interaction, and provides important mechanistic clues about how the two isoforms of {beta}-arrestins can recognize and regulate a large repertoire of GPCRs.

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Maharana, J., Sano, F. K., Sarma, P., Yadav, M. K., Duan, L., Stepniewski, T. M., Chaturvedi, M., Ranjan, A., Singh, V., Saha, S., Mahajan, G., Chami, M., Shihoya, W., Selent, J., Chung, K. Y., Banerjee, R., Nureki, O., Shukla, A. K.. 2023-07-05. Molecular insights into atypical modes of beta-arrestin interaction with seven transmembrane receptors. https://doi.org/10.1101/2023.07.05.547776

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