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Structure. 2020 Feb 4. pii: S0969-2126(20)30009-5. doi: 10.1016/j.str.2020.01.009. [Epub ahead of print]

Mammalian Retromer Is an Adaptable Scaffold for Cargo Sorting from Endosomes.

Author information

1
Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA.
2
Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA.
3
Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA; Department of Biochemistry, Vanderbilt University, Nashville, TN 37205, USA.
4
Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA.
5
National Resource for Automated Molecular Microscopy, New York Structural Biology Center, New York, NY 10027, USA.
6
Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA; Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, TN 37212, USA.
7
Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA; Department of Biochemistry, Vanderbilt University, Nashville, TN 37205, USA. Electronic address: lauren.p.jackson@vanderbilt.edu.

Abstract

Metazoan retromer (VPS26/VPS35/VPS29) associates with sorting nexins on endosomal tubules to sort proteins to the trans-Golgi network or plasma membrane. Mechanisms of metazoan retromer assembly remain undefined. We combine single-particle cryoelectron microscopy with biophysical methods to uncover multiple oligomer structures. 2D class averages reveal mammalian heterotrimers; dimers of trimers; tetramers of trimers; and flat chains. These species are further supported by biophysical solution studies. We provide reconstructions of all species, including key sub-structures (∼5 Å resolution). Local resolution variation suggests that heterotrimers and dimers adopt multiple conformations. Our structures identify a flexible, highly conserved electrostatic dimeric interface formed by VPS35 subunits. We generate structure-based mutants to disrupt this interface in vitro. Equivalent mutations in yeast demonstrate a mild cargo-sorting defect. Our data suggest the metazoan retromer is an adaptable and plastic scaffold that accommodates interactions with different sorting nexins to sort multiple cargoes from endosomes their final destinations.

KEYWORDS:

cell biology; coat proteins; membrane trafficking; single-particle cryo-EM; structural biology

PMID:
32027819
DOI:
10.1016/j.str.2020.01.009

Conflict of interest statement

Declaration of Interests The authors have no competing interests to declare.

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