The structure of the endogenous ESX-3 secretion system
- University of California, San Francisco, United States
- University of Massachusetts Medical School, United States
Abstract
The ESX (or Type VII) secretion systems are protein export systems in mycobacteria and many Gram-positive bacteria that mediate a broad range of functions including virulence, conjugation, and metabolic regulation. These systems translocate folded dimers of WXG100-superfamily protein substrates across the cytoplasmic membrane. We report the cryo-electron microscopy structure of an ESX-3 system, purified using an epitope tag inserted with recombineering into the chromosome of the model organism Mycobacterium smegmatis. The structure reveals a stacked architecture that extends above and below the inner membrane of the bacterium. The ESX-3 protomer complex is assembled from a single copy of the EccB3, EccC3, and EccE3 and two copies of the EccD3 protein. In the structure, the protomers form a stable dimer that is consistent with assembly into a larger oligomer. The ESX-3 structure provides a framework for further study of these important bacterial transporters.
Data availability
The map files have been deposited at the EMDB with code 20820. The entry is online at https://www.ebi.ac.uk/pdbe/entry/emdb/EMD-20820.The model has been deposited at the PDB with the code 6UMM. It is online at http://www.rcsb.org/structure/6UMM
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A complete structure of the ESX-3 translocon complexProtein Data Bank, 6UMM.
Article and author information
Author details
Funding
National Institutes of Health (1RO1AI128214)
- Oren S Rosenberg
National Institutes of Health (1U19AI135990-01)
- Oren S Rosenberg
National Institutes of Health (P01AI095208)
- Oren S Rosenberg
National Institutes of Health (5T32AI060537)
- Nicole Poweleit
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2019, Poweleit 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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The structure of the endogenous ESX-3 secretion system
eLife 8:e52983.
https://doi.org/10.7554/eLife.52983
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