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

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.


Peptide coverage map of mVP40. Pepsin digestion produced 77 unique overlapping peptides that resulted in 99% coverage of the mVP40 sequence.
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Figure 1: Peptide coverage map of mVP40. Pepsin digestion produced 77 unique overlapping peptides that resulted in 99% coverage of the mVP40 sequence.

Mentions: To determine the optimum digestion conditions that yielded the best peptide fragmentation pattern for mVP40, changes in the denaturant (GdnHCl) concentration (0, 0.08, 0.8, 1.6, 3.2, and 6.4 m) were employed. The most significant coverage of unique peptides was found at 0.8 m GdnHCl (final concentration in HD exchange sample = 0.5 m), where 77 unique peptides were selected and analyzed for the data generation. (The coverage map for these 77 peptides is shown in Fig. 1.)


Detection of lipid-induced structural changes of the Marburg virus matrix protein VP40 using hydrogen/deuterium exchange-mass spectrometry
Peptide coverage map of mVP40. Pepsin digestion produced 77 unique overlapping peptides that resulted in 99% coverage of the mVP40 sequence.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Peptide coverage map of mVP40. Pepsin digestion produced 77 unique overlapping peptides that resulted in 99% coverage of the mVP40 sequence.
Mentions: To determine the optimum digestion conditions that yielded the best peptide fragmentation pattern for mVP40, changes in the denaturant (GdnHCl) concentration (0, 0.08, 0.8, 1.6, 3.2, and 6.4 m) were employed. The most significant coverage of unique peptides was found at 0.8 m GdnHCl (final concentration in HD exchange sample = 0.5 m), where 77 unique peptides were selected and analyzed for the data generation. (The coverage map for these 77 peptides is shown in Fig. 1.)

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.