Related Experiment Videos
Synthesis of phage M13 coat protein and its assembly into membranes in vitro
Abstract:
The coat protein (gene 8 product) of coliphage M1O is an integral protein of the host cell membrane at all stages of virus infection. This protein, when made in a cell-free reaction, has been shown by others to have an additional NH2-terminal peptide region and is referred to as "procoat." It is initially not membrane-bound but, upon exposure to Escherichia coli membrane vesicles or to liposomes prepared from E. coli lipids, it assembles into the bilayer in an integral fashion. Much of this protein is shown to be exposed on the inner surface of the liposome. We suggest that refolding of procoat as it encounters the bilayer is sufficient to transport large segments of the peptide chain through the apolar hydrocarbon core.
Insights
Coliphage M1O coat protein, or procoat, inserts into cell membranes. Procoat refolding drives its transport through the membrane
Area of Science:
- * Molecular biology
- * Virology
- * Membrane biophysics
Background:
- * The coat protein of coliphage M1O is a key viral component.
- * In cell-free systems, this protein exists as 'procoat' with an extra N-terminal peptide.
- * Procoat is initially unbound to membranes.
Purpose of the Study:
- * To investigate the membrane insertion mechanism of coliphage M1O procoat.
- * To understand how procoat integrates into the host cell membrane.
Main Methods:
- * Studied procoat assembly in response to Escherichia coli membrane vesicles.
- * Investigated procoat integration into liposomes made from E. coli lipids.
Main Results:
- * Procoat assembles into the lipid bilayer in an integral manner upon exposure to membrane vesicles or liposomes.
- * A significant portion of the assembled protein is oriented towards the inner surface of the liposome.
- * Refolding of procoat upon bilayer interaction facilitates transport.
Conclusions:
- * Procoat's refolding is sufficient for transporting large peptide segments through the hydrophobic core of the membrane.
- * This mechanism highlights a novel pathway for viral protein integration into host membranes.