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Detection of lipid-induced structural changes of the Marburg virus matrix protein VP40 using hydrogen/deuterium exchange-mass spectrometry

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ABSTRACT

Marburg virus (MARV) is a lipid-enveloped virus from the Filoviridae family containing a negative sense RNA genome. One of the seven MARV genes encodes the matrix protein VP40, which forms a matrix layer beneath the plasma membrane inner leaflet to facilitate budding from the host cell. MARV VP40 (mVP40) has been shown to be a dimeric peripheral protein with a broad and flat basic surface that can associate with anionic phospholipids such as phosphatidylserine. Although a number of mVP40 cationic residues have been shown to facilitate binding to membranes containing anionic lipids, much less is known on how mVP40 assembles to form the matrix layer following membrane binding. Here we have used hydrogen/deuterium exchange (HDX) mass spectrometry to determine the solvent accessibility of mVP40 residues in the absence and presence of phosphatidylserine and phosphatidylinositol 4,5-bisphosphate. HDX analysis demonstrates that two basic loops in the mVP40 C-terminal domain make important contributions to anionic membrane binding and also reveals a potential oligomerization interface in the C-terminal domain as well as a conserved oligomerization interface in the mVP40 N-terminal domain. Lipid binding assays confirm the role of the two basic patches elucidated with HD/X measurements, whereas molecular dynamics simulations and membrane insertion measurements complement these studies to demonstrate that mVP40 does not appreciably insert into the hydrocarbon region of anionic membranes in contrast to the matrix protein from Ebola virus. Taken together, we propose a model by which association of the mVP40 dimer with the anionic plasma membrane facilitates assembly of mVP40 oligomers.

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Effects of phospholipid membranes on the HD exchange pattern of mVP40. Deuterium accumulation plots of peptide fragments of mVP40 that showed significant differences in the deuterium levels in the presence and absence of liposomes. Deuterium levels of mVP40 alone in the absence of lipid vesicles is shown in light blue line; VP40+L denotes mVP40 in the presence of PS containing lipid vesicles (orange line).
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Figure 6: Effects of phospholipid membranes on the HD exchange pattern of mVP40. Deuterium accumulation plots of peptide fragments of mVP40 that showed significant differences in the deuterium levels in the presence and absence of liposomes. Deuterium levels of mVP40 alone in the absence of lipid vesicles is shown in light blue line; VP40+L denotes mVP40 in the presence of PS containing lipid vesicles (orange line).

Mentions: Some of the deuterium accumulation plots of peptide fragments showed significant changes in the deuteration levels in the presence of phospholipid membranes compared with the protein alone sample (Fig. 6). These peptide fragments do not originate from the dimer interface or basic patch of mVP40 and hence we hypothesize that these peptides arise from regions of mVP40 that undergo structural changes triggered by mVP40 interaction with phospholipid membranes. For further analysis of these regions we produced a rainbow map for mVP40 in the presence of membranes representing the percentage of hydrogen/deuterium exchange for each overlapping peptide for the entire length of reaction (Fig. 7A).


Detection of lipid-induced structural changes of the Marburg virus matrix protein VP40 using hydrogen/deuterium exchange-mass spectrometry
Effects of phospholipid membranes on the HD exchange pattern of mVP40. Deuterium accumulation plots of peptide fragments of mVP40 that showed significant differences in the deuterium levels in the presence and absence of liposomes. Deuterium levels of mVP40 alone in the absence of lipid vesicles is shown in light blue line; VP40+L denotes mVP40 in the presence of PS containing lipid vesicles (orange line).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5391744&req=5

Figure 6: Effects of phospholipid membranes on the HD exchange pattern of mVP40. Deuterium accumulation plots of peptide fragments of mVP40 that showed significant differences in the deuterium levels in the presence and absence of liposomes. Deuterium levels of mVP40 alone in the absence of lipid vesicles is shown in light blue line; VP40+L denotes mVP40 in the presence of PS containing lipid vesicles (orange line).
Mentions: Some of the deuterium accumulation plots of peptide fragments showed significant changes in the deuteration levels in the presence of phospholipid membranes compared with the protein alone sample (Fig. 6). These peptide fragments do not originate from the dimer interface or basic patch of mVP40 and hence we hypothesize that these peptides arise from regions of mVP40 that undergo structural changes triggered by mVP40 interaction with phospholipid membranes. For further analysis of these regions we produced a rainbow map for mVP40 in the presence of membranes representing the percentage of hydrogen/deuterium exchange for each overlapping peptide for the entire length of reaction (Fig. 7A).

View Article: PubMed Central - PubMed

ABSTRACT

Marburg virus (MARV) is a lipid-enveloped virus from the Filoviridae family containing a negative sense RNA genome. One of the seven MARV genes encodes the matrix protein VP40, which forms a matrix layer beneath the plasma membrane inner leaflet to facilitate budding from the host cell. MARV VP40 (mVP40) has been shown to be a dimeric peripheral protein with a broad and flat basic surface that can associate with anionic phospholipids such as phosphatidylserine. Although a number of mVP40 cationic residues have been shown to facilitate binding to membranes containing anionic lipids, much less is known on how mVP40 assembles to form the matrix layer following membrane binding. Here we have used hydrogen/deuterium exchange (HDX) mass spectrometry to determine the solvent accessibility of mVP40 residues in the absence and presence of phosphatidylserine and phosphatidylinositol 4,5-bisphosphate. HDX analysis demonstrates that two basic loops in the mVP40 C-terminal domain make important contributions to anionic membrane binding and also reveals a potential oligomerization interface in the C-terminal domain as well as a conserved oligomerization interface in the mVP40 N-terminal domain. Lipid binding assays confirm the role of the two basic patches elucidated with HD/X measurements, whereas molecular dynamics simulations and membrane insertion measurements complement these studies to demonstrate that mVP40 does not appreciably insert into the hydrocarbon region of anionic membranes in contrast to the matrix protein from Ebola virus. Taken together, we propose a model by which association of the mVP40 dimer with the anionic plasma membrane facilitates assembly of mVP40 oligomers.

No MeSH data available.


Related in: MedlinePlus