ARL3 activation requires the co-GEF BART and effector-mediated turnover

  1. Yasmin ElMaghloob
  2. Begoña Sot
  3. Michael J McIlwraith
  4. Esther Garcia
  5. Tamas Yelland
  6. Shehab Ismail  Is a corresponding author
  1. Beatson Institute for Cancer Research, United Kingdom
  2. IMDEA Nanoscience, Spain

Abstract

The ADP-ribosylation factor-like 3 (ARL3) is a ciliopathy G-protein which regulates the ciliary trafficking of several lipid-modified proteins. ARL3 is activated by its guanine exchange factor (GEF) ARL13B via an unresolved mechanism. BART is described as an ARL3 effector which has also been implicated in ciliopathies, although the role of its ARL3 interaction is unknown. Here we show that, at physiological GTP:GDP levels, human ARL3GDP is weakly activated by ARL13B. However, BART interacts with nucleotide-free ARL3 and, in concert with ARL13B, efficiently activates ARL3. In addition, BART binds ARL3GTP and inhibits GTP dissociation, thereby stabilising the active G-protein; the binding of ARL3 effectors then releases BART. Finally, using live cell imaging, we show that BART accesses the primary cilium and colocalises with ARL13B. We propose a model wherein BART functions as a bona fide co-GEF for ARL3 and maintains the active ARL3GTP, until it is recycled by ARL3 effectors.

Data availability

All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided for: Figures 1A and 1B, Figures 2B, 2C, 2D, 2E, and 2F, Figures 3A,3B, 3C, 3D, 3F, Figures 4A, 4B, and 4C and Figure 5B, 5C

Article and author information

Author details

  1. Yasmin ElMaghloob

    Structural biology, Beatson Institute for Cancer Research, Glasgow, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  2. Begoña Sot

    Nanobiosystems, IMDEA Nanoscience, Madrid, Spain
    Competing interests
    The authors declare that no competing interests exist.
  3. Michael J McIlwraith

    Structural biology, Beatson Institute for Cancer Research, Glasgow, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  4. Esther Garcia

    Structural biology, Beatson Institute for Cancer Research, Glasgow, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  5. Tamas Yelland

    Structural biology, Beatson Institute for Cancer Research, Glasgow, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  6. Shehab Ismail

    Structural biology, Beatson Institute for Cancer Research, Glasgow, United Kingdom
    For correspondence
    shehab.ismail@glasgow.ac.uk
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-4150-1077

Funding

Cancer Research UK (A17196)

  • Shehab Ismail

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Suzanne R Pfeffer, Stanford University School of Medicine, United States

Version history

  1. Received: November 4, 2020
  2. Accepted: January 12, 2021
  3. Accepted Manuscript published: January 13, 2021 (version 1)
  4. Version of Record published: January 20, 2021 (version 2)

Copyright

© 2021, ElMaghloob et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Yasmin ElMaghloob
  2. Begoña Sot
  3. Michael J McIlwraith
  4. Esther Garcia
  5. Tamas Yelland
  6. Shehab Ismail
(2021)
ARL3 activation requires the co-GEF BART and effector-mediated turnover
eLife 10:e64624.
https://doi.org/10.7554/eLife.64624

Share this article

https://doi.org/10.7554/eLife.64624

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