Colicin E1 opens its hinge to plug TolC
- University of Kansas, United States
- University of Michigan, United States
- Rutgers University, United States
- Rutgers, The State University of New Jersey, United States
Abstract
The double membrane architecture of Gram-negative bacteria forms a barrier that is impermeable to most extracellular threats. Bacteriocin proteins evolved to exploit the accessible, surface-exposed proteins embedded in the outer membrane to deliver cytotoxic cargo. Colicin E1 is a bacteriocin produced by, and lethal to, Escherichia coli that hijacks the outer membrane proteins TolC and BtuB to enter the cell. Here we capture the colicin E1 translocation domain inside its membrane receptor, TolC, by high-resolution cryoEM to obtain the first reported structure of a bacteriocin bound to TolC. Colicin E1 binds stably to TolC as an open hinge through the TolC pore-an architectural rearrangement from colicin E1's unbound conformation. This binding is stable in live E. coli cells as indicated by single-molecule fluorescence microscopy. Finally, colicin E1 fragments binding to TolC plug the channel, inhibiting its native efflux function as an antibiotic efflux pump and heightening susceptibility to three antibiotic classes. In addition to demonstrating that these protein fragments are useful starting points for developing novel antibiotic potentiators, this method could be expanded to other colicins to inhibit other outer membrane protein functions.
Data availability
The manuscript has been deposited in BioRXiv BIORXIV/2019/692251CryoEM maps and models have been deposited with accession codes EMD-21960, EMD-21959, PDB ID 6WXI, and PDB ID 6WXH. The following data are publically available for the two structures:6WXH TolC + colE1Structure: https://files.rcsb.org/download/6WXH.cifEM map: https://ftp.wwpdb.org/pub/emdb/structures/EMD-21959/map/emd_21959.map.gzValidation report: https://files.rcsb.org/pub/pdb/validation_reports/wx/6wxh/6wxh_full_validation.pdf6WXI TolC aloneStructure: https://files.rcsb.org/download/6WXI.cifEM map: https://ftp.wwpdb.org/pub/emdb/structures/EMD-21960/map/emd_21960.map.gzValidation report: https://files.rcsb.org/pub/pdb/validation_reports/wx/6wxi/6wxi_full_validation.pdf
Article and author information
Author details
Jacqueline J Stevens
Ayotunde P Ikujuni
Virangika K Wimalasena
Funding
National Institute of General Medical Sciences (DP2GM128201)
- Joanna SG Slusky
National Institute of General Medical Sciences (P20GM113117)
- Joanna SG Slusky
National Institute of General Medical Sciences (P20GM103638)
- Joanna SG Slusky
Gordon and Betty Moore Foundation (Moore Inventor Fellowship)
- Joanna SG Slusky
National Institute of General Medical Sciences (P20 GM103418)
- S Jimmy Budiardjo
National Institute of General Medical Sciences (2K12GM063651)
- S Jimmy Budiardjo
National Institute of General Medical Sciences (R21-GM128022)
- Julie S Biteen
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2022, Budiardjo 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
-
- 3,293
- views
-
- 485
- downloads
-
- 16
- 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)
Colicin E1 opens its hinge to plug TolC
eLife 11:e73297.
https://doi.org/10.7554/eLife.73297
Further reading
-
- Immunology and Inflammation
- Microbiology and Infectious Disease
Circulating sexual stages of Plasmodium falciparum (Pf) can be transmitted from humans to mosquitoes, thereby furthering the spread of malaria in the population. It is well established that antibodies can efficiently block parasite transmission. In search for naturally acquired antibodies targets on sexual stages, we established an efficient method for target-agnostic single B cell activation followed by high-throughput selection of human monoclonal antibodies (mAbs) reactive to sexual stages of Pf in the form of gametes and gametocyte extracts. We isolated mAbs reactive against a range of Pf proteins including well-established targets Pfs48/45 and Pfs230. One mAb, B1E11K, was cross-reactive to various proteins containing glutamate-rich repetitive elements expressed at different stages of the parasite life cycle. A crystal structure of two B1E11K Fab domains in complex with its main antigen, RESA, expressed on asexual blood stages, showed binding of B1E11K to a repeating epitope motif in a head-to-head conformation engaging in affinity-matured homotypic interactions. Thus, this mode of recognition of Pf proteins, previously described only for Pf circumsporozoite protein (PfCSP), extends to other repeats expressed across various stages. The findings augment our understanding of immune-pathogen interactions to repeating elements of the Plasmodium parasite proteome and underscore the potential of the novel mAb identification method used to provide new insights into the natural humoral immune response against Pf.
-
- Microbiology and Infectious Disease
The type VI secretion system (T6SS) is a sophisticated, contact-dependent nanomachine involved in interbacterial competition. To function effectively, the T6SS must penetrate the membranes of both attacker and target bacteria. Structures associated with the cell envelope, like polysaccharides chains, can therefore introduce spatial separation and steric hindrance, potentially affecting the efficacy of the T6SS. In this study, we examined how the capsular polysaccharide (CPS) of Acinetobacter baumannii affects T6SS’s antibacterial function. Our findings show that the CPS confers resistance against T6SS-mediated assaults from rival bacteria. Notably, under typical growth conditions, the presence of the surface-bound capsule also reduces the efficacy of the bacterium’s own T6SS. This T6SS impairment is further enhanced when CPS is overproduced due to genetic modifications or antibiotic treatment. Furthermore, we demonstrate that the bacterium adjusts the level of the T6SS inner tube protein Hcp according to its secretion capacity, by initiating a degradation process involving the ClpXP protease. Collectively, our findings contribute to a better understanding of the dynamic relationship between T6SS and CPS and how they respond swiftly to environmental challenges.
