Structural basis for effector transmembrane domain recognition by type VI secretion system chaperones
- McMaster University, Canada
- University of Manitoba, Canada
- Max Planck Institute of Molecular Physiology, Germany
Abstract
Type VI secretion systems (T6SSs) deliver antibacterial effector proteins between neighbouring bacteria. Many effectors harbor N-terminal transmembrane domains (TMDs) implicated in effector translocation across target cell membranes. However, the distribution of these TMD-containing effectors remains unknown. Here we discover prePAAR, a conserved motif found in over 6,000 putative TMD-containing effectors encoded predominantly by 15 genera of Proteobacteria. Based on differing numbers of TMDs, effectors group into two distinct classes that both require a member of the Eag family of T6SS chaperones for export. Co-crystal structures of class I and class II effector TMD-chaperone complexes from Salmonella Typhimurium and Pseudomonas aeruginosa, respectively, reveals that Eag chaperones mimic transmembrane helical packing to stabilize effector TMDs. In addition to participating in the chaperone-TMD interface, we find that prePAAR residues mediate effector-VgrG spike interactions. Taken together, our findings reveal mechanisms of chaperone-mediated stabilization and secretion of two distinct families of T6SS membrane protein effectors.
Data availability
X-ray diffraction data for the SciW, SciW:Rhs1 complex, and Tse6:EagT6 complex have been deposited in the PDB under the accession codes 6XRB, 6XRR and 6XRF, respectively.
Article and author information
Author details
Funding
Canadian Institutes of Health Research (PJT-156129)
- John C Whitney
Natural Sciences and Engineering Research Council of Canada (RGPIN-2017-05350)
- John C Whitney
Natural Sciences and Engineering Research Council of Canada (RGPIN-2018-04968)
- Gerd Prehna
Canadian Institutes of Health Research (PJT156214)
- Andrew G McArthur
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2020, Ahmad 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
-
- 4,641
- views
-
- 522
- downloads
-
- 32
- 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)
Structural basis for effector transmembrane domain recognition by type VI secretion system chaperones
eLife 9:e62816.
https://doi.org/10.7554/eLife.62816
