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An aqueous channel for filamentous phage export.
D K Marciano1, M Russel, S M Simon
1The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Science (New York, N.Y.)
|May 29, 1999
Summary
Filamentous phage f1 uses the pIV protein channel to exit Escherichia coli without killing it. This study reveals pIV
Area of Science:
- Microbiology
- Molecular Biology
- Biophysics
Background:
- Filamentous phage f1 infects Escherichia coli, exiting without lysis.
- The phage protein pIV is hypothesized to mediate outer membrane secretion.
- Understanding phage-host interactions is crucial for bacterial genetics and phage therapy.
Purpose of the Study:
- To investigate the role of phage protein pIV in filamentous phage f1 secretion.
- To characterize the channel properties of wild-type and mutant pIV.
- To determine if pIV functions as the outer membrane channel for phage f1 exit.
Main Methods:
- Isolation and characterization of a functional pIV mutant in Escherichia coli.
- Growth assays on maltodextrins and antibiotic sensitivity tests.
- Planar lipid bilayer reconstitution of wild-type and mutant pIV channels.
Main Results:
- The pIV mutant conferred ability to metabolize large maltodextrins and increased sensitivity to hydrophilic antibiotics.
- Both wild-type and mutant pIV formed highly conductive channels in lipid bilayers.
- Mutant pIV channels exhibited significantly different gating properties (higher open probability) compared to wild-type.
Conclusions:
- The pIV protein forms a large-diameter channel across the outer membrane.
- pIV's channel properties support its role in the secretion of filamentous phage f1.
- pIV is implicated as the essential outer membrane channel for phage f1 egress.