Characterization of Atg38 and NRBF2, a fifth subunit of the autophagic Vps34/PIK3C3 complex

Yohei Ohashi, Nicolas Soler, Miguel García Ortegón, Lufei Zhang, Marie L. Kirsten, Olga Perisic, Glenn R. Masson, John E. Burke, Arjen J. Jakobi, Apostolos A. Apostolakis, Christopher M. Johnson, Maki Ohashi, Nicholas T. Ktistakis, Carsten Sachse (Lead / Corresponding author), Roger L. Williams (Lead / Corresponding author)

    Research output: Contribution to journalArticlepeer-review

    50 Citations (Scopus)

    Abstract

    The phosphatidylinositol 3-kinase Vps34 is part of several protein complexes. The structural organization of heterotetrameric complexes is starting to emerge, but little is known about organization of additional accessory subunits that interact with these assemblies. Combining hydrogen-deuterium exchange mass spectrometry (HDX-MS), X-ray crystallography and electron microscopy (EM), we have characterized Atg38 and its human ortholog NRBF2, accessory components of complex I consisting of Vps15-Vps34-Vps30/Atg6-Atg14 (yeast) and PIK3R4/VPS15-PIK3C3/VPS34-BECN1/Beclin 1-ATG14 (human). HDX-MS shows that Atg38 binds the Vps30-Atg14 subcomplex of complex I, using mainly its N-terminal MIT domain and bridges the coiled-coil I regions of Atg14 and Vps30 in the base of complex I. The Atg38 C-terminal domain is important for localization to the phagophore assembly site (PAS) and homodimerization. Our 2.2 Å resolution crystal structure of the Atg38 C-terminal homodimerization domain shows 2 segments of α-helices assembling into a mushroom-like asymmetric homodimer with a 4-helix cap and a parallel coiled-coil stalk. One Atg38 homodimer engages a single complex I. This is in sharp contrast to human NRBF2, which also forms a homodimer, but this homodimer can bridge 2 complex I assemblies.

    Original languageEnglish
    Pages (from-to)2129-2144
    Number of pages16
    JournalAutophagy
    Volume12
    Issue number11
    DOIs
    Publication statusPublished - 1 Nov 2016

    Keywords

    • Atg14
    • Atg38
    • Beclin 1
    • complex I
    • crystal structure
    • EM structure
    • NRBF2
    • Vps15
    • Vps30
    • Vps34

    ASJC Scopus subject areas

    • Molecular Biology
    • Cell Biology

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