Mechanism of cargo recognition by retromer-linked SNX-BAR proteins

PLoS Biol. 2020 Mar 9;18(3):e3000631. doi: 10.1371/journal.pbio.3000631. eCollection 2020 Mar.

Abstract

Endocytic recycling of internalized transmembrane proteins is essential for many important physiological processes. Recent studies have revealed that retromer-related Sorting Nexin family (SNX)-Bin/Amphiphysin/Rvs (BAR) proteins can directly recognize cargoes like cation-independent mannose 6-phosphate receptor (CI-MPR) and Insulin-like growth factor 1 receptor (IGF1R); however, it remains poorly understood how SNX-BARs select specific cargo proteins and whether they recognize additional ligands. Here, we discovered that the binding between SNX-BARs and CI-MPR or IGF1R is mediated by the phox-homology (PX) domain of SNX5 or SNX6 and a bipartite motif, termed SNX-BAR-binding motif (SBM), in the cargoes. Using this motif, we identified over 70 putative SNX-BAR ligands, many of which play critical roles in apoptosis, cell adhesion, signal transduction, or metabolite homeostasis. Remarkably, SNX-BARs could cooperate with both SNX27 and retromer in the recycling of ligands encompassing the SBM, PDZ-binding motif, or both motifs. Overall, our studies establish that SNX-BARs function as a direct cargo-selecting module for a large set of transmembrane proteins transiting the endosome, in addition to their roles in phospholipid recognition and biogenesis of tubular structures.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Binding Sites
  • Biological Transport
  • Computer Simulation
  • Gene Knockout Techniques
  • HeLa Cells
  • Humans
  • Protein Domains
  • Proteome / chemistry
  • Proteome / metabolism*
  • Receptor, IGF Type 2 / chemistry
  • Receptor, IGF Type 2 / metabolism*
  • Semaphorins / metabolism
  • Sorting Nexins / chemistry*
  • Sorting Nexins / genetics
  • Sorting Nexins / metabolism*

Substances

  • Proteome
  • Receptor, IGF Type 2
  • Sema4c protein, human
  • Semaphorins
  • Sorting Nexins