1. Structural Biology and Molecular Biophysics

Structure and activation mechanism of the BBSome membrane protein trafficking complex

  1. Sandeep K Singh
  2. Miao Gui
  3. Fujiet Koh
  4. Matthew CJ Yip
  5. Alan Brown  Is a corresponding author
  1. Harvard Medical School, United States
https://doi.org/10.7554/eLife.53322
Share this article
Cite this article
  1. Sandeep K Singh
  2. Miao Gui
  3. Fujiet Koh
  4. Matthew CJ Yip
  5. Alan Brown
(2020)
Structure and activation mechanism of the BBSome membrane protein trafficking complex
eLife 9:e53322.
https://doi.org/10.7554/eLife.53322
  2. Download BibTeX
  3. Download .RIS

Abstract

Bardet-Biedl syndrome (BBS) is a currently incurable ciliopathy caused by the failure to correctly establish or maintain cilia-dependent signaling pathways. Eight proteins associated with BBS assemble into the BBSome, a key regulator of the ciliary membrane proteome. We report the electron cryomicroscopy (cryo-EM) structures of the native bovine BBSome in inactive and active states at 3.1 ­and 3.5 Å resolution, respectively. In the active state, the BBSome is bound to an Arf-family GTPase (ARL6/BBS3) that recruits the BBSome to ciliary membranes. ARL6 recognizes a composite binding site formed by BBS1 and BBS7 that is occluded in the inactive state. Activation requires an unexpected swiveling of the b-propeller domain of BBS1, the subunit most frequently implicated in substrate recognition, which widens a central cavity of the BBSome. Structural mapping of disease-causing mutations suggests that pathogenesis results from folding defects and the disruption of autoinhibition and activation.

Data availability

The EM density map for the BBSome has been deposited under accession code EMD-21144 and the EM density map for the BBSome:ARL6:GTP complex has been deposited under accession code EMD-21145. Masks and maps from multibody refinement are included as additional maps in these depositions. The corresponding atomic models have been deposited under accession codes 6VBU and 6VBV.

The following data sets were generated

Article and author information

Author details

  1. Sandeep K Singh

    Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
    Competing interests
    No competing interests declared.

  2. Miao Gui

    Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
    Competing interests
    No competing interests declared.

  3. Fujiet Koh

    Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
    Competing interests
    Fujiet Koh, is affiliated with Thermo Fisher Scientific. The author has no financial interests to declare.

  4. Matthew CJ Yip

    Department of Cell Biology, Harvard Medical School, Boston, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-2505-9987

  5. Alan Brown

    Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
    For correspondence
    alan_brown@hms.harvard.edu
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-0021-0476

Funding

Pew Charitable Trusts

  • Alan Brown

Internal Retinal Research Foundation

  • Alan Brown

E. Matilda Ziegler Foundation for the Blind

  • Alan Brown

Richard and Susan Smith Family Foundation

  • Alan Brown

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

Copyright

© 2020, Singh 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.

Metrics

  • 6,285
    views
  • 862
    downloads
  • 67
    citations

Views, downloads and citations are aggregated across all versions of this paper published by eLife.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Sandeep K Singh
  2. Miao Gui
  3. Fujiet Koh
  4. Matthew CJ Yip
  5. Alan Brown
(2020)
Structure and activation mechanism of the BBSome membrane protein trafficking complex
eLife 9:e53322.
https://doi.org/10.7554/eLife.53322

Share this article

https://doi.org/10.7554/eLife.53322

Categories and tags

Further reading

    1. Structural Biology and Molecular Biophysics

    Structure of the human BBSome core complex

    Björn Udo Klink, Christos Gatsogiannis ... Stefan Raunser
    Research Article Updated

    The BBSome is a heterooctameric protein complex that plays a central role in primary cilia homeostasis. Its malfunction causes the severe ciliopathy Bardet-Biedl syndrome (BBS). The complex acts as a cargo adapter that recognizes signaling proteins such as GPCRs and links them to the intraflagellar transport machinery. The underlying mechanism is poorly understood. Here we present a high-resolution cryo-EM structure of a human heterohexameric core subcomplex of the BBSome. The structure reveals the architecture of the complex in atomic detail. It explains how the subunits interact with each other and how disease-causing mutations hamper this interaction. The complex adopts a conformation that is open for binding to membrane-associated GTPase Arl6 and a large positively charged patch likely strengthens the interaction with the membrane. A prominent negatively charged cleft at the center of the complex is likely involved in binding of positively charged signaling sequences of cargo proteins.

    1. Structural Biology and Molecular Biophysics

    Intraflagellar Transport: Moving proteins along in the cilium

    Narcis Adrian Petriman, Esben Lorentzen
    Insight

    The structures of the bovine and human BBSome reveal that a conformational change is required to recruit the complex to the ciliary membrane.

    1. Computational and Systems Biology
    2. Structural Biology and Molecular Biophysics

    Discovery of a heparan sulfate binding domain in monkeypox virus H3 as an anti-poxviral drug target combining AI and MD simulations

    Bin Zheng, Meimei Duan ... Peng Zheng
    Research Article

    Viral adhesion to host cells is a critical step in infection for many viruses, including monkeypox virus (MPXV). In MPXV, the H3 protein mediates viral adhesion through its interaction with heparan sulfate (HS), yet the structural details of this interaction have remained elusive. Using AI-based structural prediction tools and molecular dynamics (MD) simulations, we identified a novel, positively charged α-helical domain in H3 that is essential for HS binding. This conserved domain, found across orthopoxviruses, was experimentally validated and shown to be critical for viral adhesion, making it an ideal target for antiviral drug development. Targeting this domain, we designed a protein inhibitor, which disrupted the H3-HS interaction, inhibited viral infection in vitro and viral replication in vivo, offering a promising antiviral candidate. Our findings reveal a novel therapeutic target of MPXV, demonstrating the potential of combination of AI-driven methods and MD simulations to accelerate antiviral drug discovery.