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High-throughput Measurement of Plasma Membrane Resealing Efficiency in Mammalian Cells
Published on: January 7, 2019
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Incomplete pneumolysin oligomers form membrane pores.
Andreas F-P Sonnen1, Jürgen M Plitzko, Robert J C Gilbert
1Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
Open Biology
|April 25, 2014
Summary
Pneumolysin, a pore-forming protein, can create smaller membrane lesions through incomplete ring structures. This finding is relevant to related proteins involved in cell membrane damage.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Pneumolysin is a cholesterol-dependent cytolysin (CDC) that forms pores in cell membranes.
- CDCs assemble into large ring structures, but also form smaller lesions of low conductance.
- The mechanism of smaller pore formation by incomplete oligomers was previously unclear.
Purpose of the Study:
- To investigate if arc-like oligomers of pneumolysin can form smaller functional pores.
- To determine the structures of pneumolysin oligomers on model lipid membranes.
Main Methods:
- Cryo-electron tomography was used to visualize pneumolysin oligomers on model lipid membranes.
- Sub-tomogram classification and averaging were employed to resolve low-resolution structures.
- Distinction between pre-pore and pore states was made by analyzing membrane presence within oligomers.
Main Results:
- Both complete (ring) and incomplete (arc) oligomers were observed in pre-pore and pore states.
- Arc-shaped oligomeric assemblies of pneumolysin were found to form functional pores.
- These findings suggest a structural basis for the formation of smaller pneumolysin pores.
Conclusions:
- Incomplete (arc) oligomers of pneumolysin can indeed form pores in lipid bilayers.
- This provides a structural explanation for the formation of smaller lesions by pneumolysin.
- Findings are relevant to the broader family of CDCs and related membrane attack proteins.
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