The cryo-EM structure of the SNX-BAR Mvp1 tetramer.

Dapeng Sun, Natalia V Varlakhanova, Bryan A Tornabene, Rajesh Ramachandran, Peijun Zhang, Marijn G J Ford

Nature communications 2020 Mar 20

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Sorting nexins (SNX) are a family of PX domain-containing proteins with pivotal roles in trafficking and signaling. SNX-BARs, which also have a curvature-generating Bin/Amphiphysin/Rvs (BAR) domain, have membrane-remodeling functions, particularly at the endosome. The minimal PX-BAR module is a dimer mediated by BAR-BAR interactions. Many SNX-BAR proteins, however, additionally have low-complexity N-terminal regions of unknown function. Here, we present the cryo-EM structure of the full-length SNX-BAR Mvp1, which is an autoinhibited tetramer. The tetramer is a dimer of dimers, wherein the membrane-interacting BAR surfaces are sequestered and the PX lipid-binding sites are occluded. The N-terminal low-complexity region of Mvp1 is essential for tetramerization. Mvp1 lacking its N-terminus is dimeric and exhibits enhanced membrane association. Membrane binding and remodeling by Mvp1 therefore requires unmasking of the PX and BAR domain lipid-interacting surfaces. This work reveals a tetrameric configuration of a SNX-BAR protein that provides critical insight into SNX-BAR function and regulation.

Citation

Dapeng Sun, Natalia V Varlakhanova, Bryan A Tornabene, Rajesh Ramachandran, Peijun Zhang, Marijn G J Ford. The cryo-EM structure of the SNX-BAR Mvp1 tetramer. Nature communications. 2020 Mar 20;11(1):1506