Crystal structure of β-arrestin 2 in complex with an atypical chemokine receptor phosphopeptide reveals an alternative active conformation

Kyungjin Mina, Hye-Jin Yoona, Ji Young Parkb, Mithu Baidyac, Hemlata Dwivedic, Jagannath Maharanac, Ka Young Chungb, Arun K. Shuklac, Hyung Ho Lee

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Oct 02, 2019
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Received Date: 23rd September 19

β-arrestins (βarrs) critically regulate signaling and trafficking of G protein-coupled receptors (GPCRs), the largest family of drug targets in the human genome, and there are two isoforms of βarrs: βarr1 and βarr2. Most GPCRs interact with both the heterotrimeric G-proteins and βarrs, inducing distinct downstream signal transduction. However, certain chemokine receptors lack functional G-protein coupling, but they can efficiently recruit βarrs upon agonist-stimulation, and they are referred to as atypical chemokine receptors (ACKRs). Receptor phosphorylation is a key determinant for the binding of βarrs, and understanding the intricate details of receptor-βarr interaction is the next frontier in GPCR structural biology. To date, the high-resolution structures of active βarr1 have been revealed, but the activation mechanism of βarr2 by a phosphorylated GPCR remains elusive. Here, we present a 1.95 Å crystal structure of βarr2 in complex with a phosphopeptide (C7pp) derived from the carboxyl-terminus of ACKR3, also known as CXCR7. The structure of C7pp-bound βarr2 reveals key differences from the previously determined active conformation of βarr1. One of the key differences is that C7pp-bound βarr2 shows a relatively small inter-domain rotation. An antibody-fragment-based conformational sensor and hydrogen/deuterium exchange experiments further corroborate structural features and suggest that the determined structure is an alternative active conformation of βarr2.

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This is an abstract of a preprint hosted on an independent third party site. It has not been peer reviewed but is currently under consideration at Nature Communications.

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