7KHW

Cryo-EM structure of enteropathogenic Escherichia coli type III secretion system EspA filament

Summary for 7KHW

• Entry DOI: 10.2210/pdb7khw/pdb
• EMDB information: 22881
• Descriptor: Translocon EspA (1 entity in total)
• Functional Keywords: type iii secretion system (t3ss), espa filament, helical reconstruction, protein fibril
• Biological source: Escherichia coli O127:H6 (strain E2348/69 / EPEC)
• Total number of polymer chains: 50
• Total formula weight: 1024140.55

Authors

Zheng, W.,Ilangovan, A.,Costa, T.R.D.,Egelman, E.H. (deposition date: 2020-10-22, release date: 2020-12-23, Last modification date: 2024-03-06)

Primary citation

Zheng, W.,Pena, A.,Ilangovan, A.,Clark, J.N.,Frankel, G.,Egelman, E.H.,Costa, T.R.D.
Cryoelectron-microscopy structure of the enteropathogenic Escherichia coli type III secretion system EspA filament.
Proc.Natl.Acad.Sci.USA, 118:-, 2021

PubMed Abstract: Enteropathogenic (EPEC) and enterohemorrhagic (EHEC) utilize a macromolecular type III secretion system (T3SS) to inject effector proteins into eukaryotic cells. This apparatus spans the inner and outer bacterial membranes and includes a helical needle protruding into the extracellular space. Thus far observed only in EPEC and EHEC and not found in other pathogenic Gram-negative bacteria that have a T3SS is an additional helical filament made by the EspA protein that forms a long extension to the needle, mediating both attachment to eukaryotic cells and transport of effector proteins through the intestinal mucus layer. Here, we present the structure of the EspA filament from EPEC at 3.4 Å resolution. The structure reveals that the EspA filament is a right-handed 1-start helical assembly with a conserved lumen architecture with respect to the needle to ensure the seamless transport of unfolded cargos en route to the target cell. This functional conservation is despite the fact that there is little apparent overall conservation at the level of sequence or structure with the needle. We also unveil the molecular details of the immunodominant EspA epitope that can now be exploited for the rational design of epitope display systems.

PubMed: 33397726
DOI: 10.1073/pnas.2022826118

Experimental method

ELECTRON MICROSCOPY (3.4 Å)