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From Constructs to Crystals – Towards Structure Determination of β-barrel Outer Membrane Proteins
Published on: July 4, 2016
Intrinsically disordered protein threads through the bacterial outer-membrane porin OmpF
Nicholas G Housden1, Jonathan T S Hopper, Natalya Lukoyanova
1Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
Science (New York, N.Y.)
|July 2, 2013
Summary
Bacteriocin colicin E9 (ColE9) uses the OmpF porin to form a translocon for cell entry. An intrinsically disordered protein domain threads through OmpF pores to trigger cell death.
Area of Science:
- Microbiology
- Structural Biology
- Molecular Biology
Background:
- Porins are outer-membrane proteins crucial for solute transport and are implicated in cell death.
- Bacteriocins, like colicin E9 (ColE9), are protein toxins that target bacteria.
- The OmpF porin is a key component of the outer membrane in Escherichia coli.
Purpose of the Study:
- To investigate the mechanism by which colicin E9 assembles a cytotoxic translocon using the OmpF porin.
- To elucidate how ColE9's intrinsically disordered N-terminal domain interacts with OmpF to initiate cell import.
Main Methods:
- Studied the assembly of the ColE9-OmpF translocon on the surface of Escherichia coli.
- Utilized structural and biochemical techniques to analyze protein-protein interactions.
Main Results:
- Colicin E9's N-terminal domain threads through two OmpF subunits in opposite directions.
- This threading captures the target TolB protein in a fixed orientation, initiating colicin import.
- Demonstrated that intrinsically disordered proteins can traverse narrow porin channels.
Conclusions:
- Colicin E9 exploits the OmpF porin structure to form a translocon for bacterial cell entry.
- The mechanism involves an intrinsically disordered protein domain tunneling through the porin to deliver a signal for cell death.
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