Poster Presentation The 47th Lorne Conference on Protein Structure and Function 2022

Mechanistic basis for SNX27-Retromer coupling to ESCPE-1 in promoting endosomal cargo recycling (#319)

Qian Guo 1 , Boris Simonetti 2 , Manuel Gimenez-Andres 2 , Kai-en Chen 1 , Edmund Moody 3 , Ashley Evans 2 , Chris Danson 2 , Tom Williams 3 , Peter Cullen 2 , Brett Collins 1
  1. Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
  2. School of Biochemistry, Faculty of Life Sciences, Biomedical Sciences Building, University of Bristol, Bristol, BS8 1TD, UK
  3. School of Biological Sciences, Faculty of Life Sciences, Life Sciences Building, University of Bristol, Bristol, BS8 1TQ, UK

Maintenance of appropriate levels of endocytic trafficking and subsequent sorting of transmembrane ‘cargo’ proteins in endosomes is essential for cellular function. Sorting nexin-27 (SNX27)-Retromer is an endosomal sorting complex that orchestrates endosome-to-plasma membrane recycling of hundreds of internalized receptors, channels and transporters, enzymes, and adhesion molecules. While SNX27-Retromer is essential for development, subtle functional defects are observed in human disease, most notably neurodegenerative and neurological disorders. Achieving a thorough mechanistic dissection of SNX27-Retromer is central to understanding endosomal sorting in health and disease. Here we combine biochemical, structural, and cellular analyses to establish the mechanistic basis through which SNX27-Retromer couples to the membrane tubulating ESCPE-1 complex (Endosomal SNX-BAR sorting complex for promoting exit 1). We show that a conserved surface in the FERM (4.1/ezrin/radixin/moesin) domain of SNX27 directly binds acidic-Asp-Leu-Phe (aDLF) motifs in the disordered amino-termini of the SNX1 and SNX2 subunits of ESCPE-1. This interaction hands-over SNX27-Retromer captured integral membrane proteins into ESCPE-1 tubular profiles to promote their cell surface recycling.