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

Bronwyn J E Lyons; Claire E Atkinson; Wanyin Deng; Antonio Serapio-Palacios; B Brett Finlay; Natalie C J Strynadka

doi:10.1016/j.str.2020.12.009

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

Structure. 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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amino Acid Substitution
Cryoelectron Microscopy
Enteropathogenic Escherichia coli
Escherichia coli Proteins / chemistry*
Escherichia coli Proteins / genetics
Escherichia coli Proteins / metabolism
HeLa Cells
Humans
Protein Conformation
Type III Secretion Systems / chemistry*
Type III Secretion Systems / genetics
Type III Secretion Systems / metabolism

Substances

Escherichia coli Proteins
EspA protein, E coli
Type III Secretion Systems

Abstract

Publication types

MeSH terms

Substances

Grants and funding