Structural basis of human ORP1-Rab7 interaction for the late-endosome and lysosome targeting

PLoS One. 2019 Feb 5;14(2):e0211724. doi: 10.1371/journal.pone.0211724. eCollection 2019.

Abstract

Oxysterol-binding protein (OSBP) and OSBP-related proteins (ORPs) constitute a family of lipid transfer proteins conserved in eukaryotes. ORP1 transports cholesterol at the interface between the late endosomes/lysosomes (LELs) and the endoplasmic reticulum (ER). ORP1 is targeted to the endosomal membranes by forming a tripartite complex with the LE GTPase Rab7 and its effector RILP (Rab7-interacting lysosomal protein). Here, we determined the crystal structure of human ORP1 ANK domain in complex with the GTP-bound form of Rab7. ORP1 ANK binds to the helix α3 of Rab7 located away from the switching regions, which makes the interaction independent of the nucleotide-binding state of Rab7. Thus, the effector-interacting switch regions of Rab7 are accessible for RILP binding, allowing formation of the ORP1-Rab7-RILP complex. ORP1 ANK binds to Rab7 and the Rab7-RILP complex with similar micro-molar affinities, which is consistent with the independence binding of ORP1 and RILP to Rab7. The structural model of the ORP1-Rab7-RILP complex correlates with the recruitment of ORP1 at the LEL-ER interface and the role in lipid transport and regulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Calorimetry
  • Cloning, Molecular
  • Crystallography, X-Ray
  • Endoplasmic Reticulum / metabolism
  • Endosomes / metabolism*
  • Humans
  • Lysosomes / metabolism*
  • Protein Binding
  • Protein Conformation
  • Receptors, Steroid / chemistry
  • Receptors, Steroid / metabolism*
  • rab GTP-Binding Proteins / chemistry
  • rab GTP-Binding Proteins / metabolism*
  • rab7 GTP-Binding Proteins

Substances

  • Receptors, Steroid
  • oxysterol binding protein
  • rab7 GTP-Binding Proteins
  • rab7 GTP-binding proteins, human
  • rab GTP-Binding Proteins

Grants and funding

This work was supported by the National Research Foundation of Korea grant funded by the Ministry of Education, Science and Technology (Grant NRF-2017R1A2B4004914 to YJI). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.