The structure of the endogenous ESX-3 secretion system
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
-
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.
Metrics
-
- 4,318
- views
-
- 528
- downloads
-
- 75
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.