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Direct observation of membrane insertion by enveloped virus matrix proteins by phosphate displacement.

Neuman BW, Kiss G, Al-Mulla HM, Dokland T, Buchmeier MJ, Weikl T, Schley D - PLoS ONE (2013)

Bottom Line: Enveloped virus release is driven by poorly understood proteins that are functional analogs of the coat protein assemblies that mediate intracellular vesicle trafficking.We used differential electron density mapping to detect membrane integration by membrane-bending proteins from five virus families.This demonstrates that virus matrix proteins replace an unexpectedly large portion of the lipid content of the inner membrane face, a generalized feature likely to play a role in reshaping cellular membranes.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Reading, Reading, Berkshire, United Kingdom. b.w.neuman@reading.ac.uk

ABSTRACT
Enveloped virus release is driven by poorly understood proteins that are functional analogs of the coat protein assemblies that mediate intracellular vesicle trafficking. We used differential electron density mapping to detect membrane integration by membrane-bending proteins from five virus families. This demonstrates that virus matrix proteins replace an unexpectedly large portion of the lipid content of the inner membrane face, a generalized feature likely to play a role in reshaping cellular membranes.

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Lipid phosphate is displaced in the presence of viral matrix proteins.Relative electron microscope signal intensity is shown on the vertical axis with average background intensity marked by a gray triangle. The horizontal axis represents radial distance from the midpoint of the membrane. The boundaries of the inner (In) and outer (Out) membrane phosphate rings measured in this study are shown for viruses (black), empty vesicles (blue) and virus-like particles that contain surface glycoproteins but lack a visible matrix layer (GP vesicles; red). Approximate positions of the nucleoprotein (core; 3MX5), matrix (2KO5) and glycoprotein (3KAS) structures in arenavirus particles are shown as a reference. P-values relate to comparison of inner phosphate ring signals with viruses as described in the Methods section. Comparisons are omitted where GP vesicles were not available. Virus names are abbreviated as follows: Lymphocytic choriomeningitis virus (LCMV), Junin virus (JUNV), Pichinde virus (PICV), Tacaribe virus (TCRV), Porcine respiratory and reproductive syndrome virus (PRRSV), Feline coronavirus (FCoV), Mouse hepatitis virus (MHV), Severe acute respiratory syndrome coronavirus (SARS-CoV), Influenza A virus (FLUAV), Influenza B virus (FLUBV), Murine leukaemia virus (MLV).
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pone-0057916-g003: Lipid phosphate is displaced in the presence of viral matrix proteins.Relative electron microscope signal intensity is shown on the vertical axis with average background intensity marked by a gray triangle. The horizontal axis represents radial distance from the midpoint of the membrane. The boundaries of the inner (In) and outer (Out) membrane phosphate rings measured in this study are shown for viruses (black), empty vesicles (blue) and virus-like particles that contain surface glycoproteins but lack a visible matrix layer (GP vesicles; red). Approximate positions of the nucleoprotein (core; 3MX5), matrix (2KO5) and glycoprotein (3KAS) structures in arenavirus particles are shown as a reference. P-values relate to comparison of inner phosphate ring signals with viruses as described in the Methods section. Comparisons are omitted where GP vesicles were not available. Virus names are abbreviated as follows: Lymphocytic choriomeningitis virus (LCMV), Junin virus (JUNV), Pichinde virus (PICV), Tacaribe virus (TCRV), Porcine respiratory and reproductive syndrome virus (PRRSV), Feline coronavirus (FCoV), Mouse hepatitis virus (MHV), Severe acute respiratory syndrome coronavirus (SARS-CoV), Influenza A virus (FLUAV), Influenza B virus (FLUBV), Murine leukaemia virus (MLV).

Mentions: The intensity of the virus inner phosphate rings differed strongly from internal vesicle controls, with a significantly lower signal in all 11 viruses considered (Fig. 3). The inner phosphate ring (area marked In) in native virus particles was only 45±23% (blue vs. black, n = 11) that of the vesicles and 46±31% (red vs. black, n = 5) that of GP vesicles, demonstrating that the reduction in inner leaflet phosphate is matrix protein dependent, and not solely due to transmembrane surface glycoproteins. To our knowledge, this is the first time lipid displacement has been tracked to demonstrate membrane protein integration.


Direct observation of membrane insertion by enveloped virus matrix proteins by phosphate displacement.

Neuman BW, Kiss G, Al-Mulla HM, Dokland T, Buchmeier MJ, Weikl T, Schley D - PLoS ONE (2013)

Lipid phosphate is displaced in the presence of viral matrix proteins.Relative electron microscope signal intensity is shown on the vertical axis with average background intensity marked by a gray triangle. The horizontal axis represents radial distance from the midpoint of the membrane. The boundaries of the inner (In) and outer (Out) membrane phosphate rings measured in this study are shown for viruses (black), empty vesicles (blue) and virus-like particles that contain surface glycoproteins but lack a visible matrix layer (GP vesicles; red). Approximate positions of the nucleoprotein (core; 3MX5), matrix (2KO5) and glycoprotein (3KAS) structures in arenavirus particles are shown as a reference. P-values relate to comparison of inner phosphate ring signals with viruses as described in the Methods section. Comparisons are omitted where GP vesicles were not available. Virus names are abbreviated as follows: Lymphocytic choriomeningitis virus (LCMV), Junin virus (JUNV), Pichinde virus (PICV), Tacaribe virus (TCRV), Porcine respiratory and reproductive syndrome virus (PRRSV), Feline coronavirus (FCoV), Mouse hepatitis virus (MHV), Severe acute respiratory syndrome coronavirus (SARS-CoV), Influenza A virus (FLUAV), Influenza B virus (FLUBV), Murine leukaemia virus (MLV).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3585246&req=5

pone-0057916-g003: Lipid phosphate is displaced in the presence of viral matrix proteins.Relative electron microscope signal intensity is shown on the vertical axis with average background intensity marked by a gray triangle. The horizontal axis represents radial distance from the midpoint of the membrane. The boundaries of the inner (In) and outer (Out) membrane phosphate rings measured in this study are shown for viruses (black), empty vesicles (blue) and virus-like particles that contain surface glycoproteins but lack a visible matrix layer (GP vesicles; red). Approximate positions of the nucleoprotein (core; 3MX5), matrix (2KO5) and glycoprotein (3KAS) structures in arenavirus particles are shown as a reference. P-values relate to comparison of inner phosphate ring signals with viruses as described in the Methods section. Comparisons are omitted where GP vesicles were not available. Virus names are abbreviated as follows: Lymphocytic choriomeningitis virus (LCMV), Junin virus (JUNV), Pichinde virus (PICV), Tacaribe virus (TCRV), Porcine respiratory and reproductive syndrome virus (PRRSV), Feline coronavirus (FCoV), Mouse hepatitis virus (MHV), Severe acute respiratory syndrome coronavirus (SARS-CoV), Influenza A virus (FLUAV), Influenza B virus (FLUBV), Murine leukaemia virus (MLV).
Mentions: The intensity of the virus inner phosphate rings differed strongly from internal vesicle controls, with a significantly lower signal in all 11 viruses considered (Fig. 3). The inner phosphate ring (area marked In) in native virus particles was only 45±23% (blue vs. black, n = 11) that of the vesicles and 46±31% (red vs. black, n = 5) that of GP vesicles, demonstrating that the reduction in inner leaflet phosphate is matrix protein dependent, and not solely due to transmembrane surface glycoproteins. To our knowledge, this is the first time lipid displacement has been tracked to demonstrate membrane protein integration.

Bottom Line: Enveloped virus release is driven by poorly understood proteins that are functional analogs of the coat protein assemblies that mediate intracellular vesicle trafficking.We used differential electron density mapping to detect membrane integration by membrane-bending proteins from five virus families.This demonstrates that virus matrix proteins replace an unexpectedly large portion of the lipid content of the inner membrane face, a generalized feature likely to play a role in reshaping cellular membranes.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Reading, Reading, Berkshire, United Kingdom. b.w.neuman@reading.ac.uk

ABSTRACT
Enveloped virus release is driven by poorly understood proteins that are functional analogs of the coat protein assemblies that mediate intracellular vesicle trafficking. We used differential electron density mapping to detect membrane integration by membrane-bending proteins from five virus families. This demonstrates that virus matrix proteins replace an unexpectedly large portion of the lipid content of the inner membrane face, a generalized feature likely to play a role in reshaping cellular membranes.

Show MeSH
Related in: MedlinePlus