Cryo-EM structure of the EspA filament from enteropathogenic Escherichia coli: Revealing the mechanism of effector translocation in the T3SS

Bronwyn J E Lyons¹, Claire E Atkinson², Wanyin Deng³, Antonio Serapio-Palacios⁴, B Brett Finlay⁵, Natalie C J Strynadka⁶

Affiliations

¹ Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; Centre for Blood Research, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
² Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; Centre for Blood Research, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; HRMEM facility, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
³ Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
⁴ Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
⁵ Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
⁶ Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; Centre for Blood Research, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; HRMEM facility, University of British Columbia, Vancouver, BC V6T 1Z3, Canada. Electronic address: ncjs@mail.ubc.ca.

PMID: 33453150
DOI: 10.1016/j.str.2020.12.009

Free article

Cryo-EM structure of the EspA filament from enteropathogenic Escherichia coli: Revealing the mechanism of effector translocation in the T3SS

Bronwyn J E Lyons et al. Structure. 2021.

Free article

. 2021 May 6;29(5):479-487.e4.

doi: 10.1016/j.str.2020.12.009. Epub 2021 Jan 15.

Authors

Bronwyn J E Lyons¹, Claire E Atkinson², Wanyin Deng³, Antonio Serapio-Palacios⁴, B Brett Finlay⁵, Natalie C J Strynadka⁶

Affiliations

¹ Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; Centre for Blood Research, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
² Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; Centre for Blood Research, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; HRMEM facility, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
³ Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
⁴ Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
⁵ Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
⁶ Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; Centre for Blood Research, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; HRMEM facility, University of British Columbia, Vancouver, BC V6T 1Z3, Canada. Electronic address: ncjs@mail.ubc.ca.

PMID: 33453150
DOI: 10.1016/j.str.2020.12.009

Abstract

The type III secretion system (T3SS) is a virulence mechanism employed by Gram-negative pathogens. The T3SS forms a proteinaceous channel that projects a needle into the extracellular medium where it interacts with the host cell to deliver virulence factors. Enteropathogenic Escherichia coli (EPEC) is unique in adopting a needle extension to the T3SS-a filament formed by EspA-which is absolutely required for efficient colonization of the gut. Here, we describe the cryoelectron microscopy structure of native EspA filaments from EPEC at 3.6-Å resolution. Within the filament, positively charged residues adjacent to a hydrophobic groove line the lumen of the filament in a spiral manner, suggesting a mechanism of substrate translocation mediated via electrostatics. Using structure-guided mutagenesis, in vivo studies corroborate the role of these residues in secretion and translocation function. The high-resolution structure of the EspA filament could aid in structure-guided drug design of antivirulence therapeutics.

Keywords: EPEC virulence; T3SS; antibiotic resistance; cryoelectron microscopy; vaccine targets.

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Conflict of interest statement

Declaration of interests The authors declare no competing interests.

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Cryo-EM structure of the EspA filament from enteropathogenic Escherichia coli: Revealing the mechanism of effector translocation in the T3SS

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Cryo-EM structure of the EspA filament from enteropathogenic Escherichia coli: Revealing the mechanism of effector translocation in the T3SS

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