Structural characterization of the retromer cargo recognition sub-complex — ASN Events

Structural characterization of the retromer cargo recognition sub-complex (#240)

Natalya Leneva 1 , Suzanne Norwood 1 , Rajesh Ghai 1 , Nathan Cowieson 2 , Anthony Duff 3 , Kathleen Wood 3 , Brett Collins
  1. Institut for Molecular Bioscience, Brisbane, QLD, Australia
  2. Australian Synchrotron, Melbourne, VIC, Australia
  3. Australian Nuclear Science and Technology Organisation, Sydney

Retromer is a peripheral membrane protein complex that plays a key role in cargo export from the endosomal network. It is involved in many physiological, developmental and pathological processes including Wnt signaling, toxin transport and amyloid production in Alzheimer’s disease.

The classical retromer complex consists of five proteins that can be classified into two sub-complexes. One sub-complex contains a heterodimer of proteins from the sorting nexin family (SNX1/SNX2 and SNX5/SNX6), containing Bin-Amphiphysin-Rvs domains (SNX-BAR proteins) that can drive and/or sense membrane deformation and tubulation. The cargo-selective sub-complex is heterotrimeric and consists of VPS26, VPS29 and VPS35. While there is noticeable diversity of sorting nexins between species, the cargo-selective sub-complex is highly conserved across all eukaryotes. Therefore the core functional component of the retromer complex is considered to be the cargo selective trimer.

Using the SAXS/WAXS and MX beamlines at the Australian Synchrotron, we have acquired crystallographic and small angle scattering data to determine how the core cargo recognition sub-complex assembles. We are also currently exploring the structure of these proteins in the thermophilic fungus Chaetomium thermophilum. Recently, we crystallized and solved the structure of VPS29. The crystallization of VPS26 and VPS35, as well as co-crystallization experiments are currently in progress. We are using this structural information in combination with biochemical and biological studies in a synergistic approach to understand retromer-mediated endosomal protein sorting and how this fascinating protein complex contributes to a diverse set of cellular processes. The structural characterization of the cargo-selective complex of retromer and its interacting partners will provide additional insight into retromer specificity and function.