Binding of equine infectious anemia virus matrix protein to membrane bilayers involves multiple interactions

Provitera, Paxton; Bouamr, Fadilla; Murray, Diana; Carter, Carol; Scarlata, Suzanne

doi:10.1006/jmbi.1999.3482

Cited by 29 publications

(52 citation statements)

References 33 publications

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“…RSV Gag is unusual in that it is not myristylated, suggesting a simpler binding mechanism. To date, studies with purified Gag proteins and liposomes of defined composition have been limited to HIV-1 (18,81) and EIAV (70). In those experiments, membrane associations were monitored indirectly by fluorescence-quenching techniques.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, sedimentation assays cannot unambiguously distinguish membrane-bound proteins from protein aggregates. In a second type of protocol, purified MA proteins derived by Escherichia coli expression were used in fluorescence-quenching studies to monitor membrane associations (18,70,81). Both EIAV MA (which is not naturally myristylated) and unmyristylated HIV-1 MA were reported to interact tightly with acidic liposomes, apparently reinforcing the importance of electrostatic interactions for Gag-membrane binding (18,70).…”

mentioning

confidence: 99%

“…In a second type of protocol, purified MA proteins derived by Escherichia coli expression were used in fluorescence-quenching studies to monitor membrane associations (18,70,81). Both EIAV MA (which is not naturally myristylated) and unmyristylated HIV-1 MA were reported to interact tightly with acidic liposomes, apparently reinforcing the importance of electrostatic interactions for Gag-membrane binding (18,70). However, the report by the same authors that HIV-1 CA, which presumably does not interact with membranes in vivo, also associates with acidic membranes with a high affinity (18) calls into question the biological relevance of the results from the fluorescence-based assays.…”

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confidence: 99%

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Biochemical Characterization of Rous Sarcoma Virus MA Protein Interaction with Membranes

Dalton

Murray

et al. 2005

J Virol

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108

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The MA domain of retroviral Gag proteins mediates association with the host cell membrane during assembly. The biochemical nature of this interaction is not well understood. We have used an in vitro flotation assay to directly measure Rous sarcoma virus (RSV) MA-membrane interaction in the absence of host cell factors. The association of purified MA and MA-containing proteins with liposomes of defined composition was electrostatic in nature and depended upon the presence of a biologically relevant concentration of negatively charged lipids. A mutant MA protein known to be unable to promote Gag membrane association and budding in vivo failed to bind to liposomes. These results were supported by computational modeling. The intrinsic affinity of RSV MA for negatively charged membranes appears insufficient to promote efficient plasma membrane binding during assembly. However, an artificially dimerized form of MA bound to liposomes by at least an order of magnitude more tightly than monomeric MA. This result suggests that the clustering of MA domains, via Gag-Gag interactions during virus assembly, drives membrane association in vivo.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Biochemical Characterization of Rous Sarcoma Virus MA Protein Interaction with Membranes

Dalton

Murray

et al. 2005

J Virol

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108

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“…The RSV M domain may exploit this threedimensional conformation to bring basic residues together along one face of the molecule; this basic region might serve an analogous function in stabilizing interactions with the membrane phospholipids as the basic motif in the HIV MA sequence. Indeed, genetic evidence from RSV Gag and biochemical analysis of EIAV MA suggest that basic residues contribute to electrostatic interactions crucial to membrane association and viral assembly (3,35,37). However, it is possible that additional membrane-binding signals that do not rely on electrostatic interactions exist within nonmyristoylated Gag proteins.…”

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confidence: 99%

“…However, it is possible that additional membrane-binding signals that do not rely on electrostatic interactions exist within nonmyristoylated Gag proteins. Evidence from studies of the EIAV MA protein support this idea, as EIAV MA binds equally well to electrically neutral and negatively charged lipid bilayers (37).…”

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Specificity of Plasma Membrane Targeting by the Rous Sarcoma Virus Gag Protein

Scheifele

Rhoads²,

Parent

2003

J Virol

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Budding of C-type retroviruses begins when the viral Gag polyprotein is directed to the plasma membrane by an N-terminal membrane-binding (M) domain. While dispersed basic amino acids within the M domain are critical for stable membrane association and consequent particle assembly, additional residues or motifs may be required for specific plasma membrane targeting and binding. We have identified an assembly-defective Rous sarcoma virus (RSV) Gag mutant that retains significant membrane affinity despite having a deletion of the fourth alpha-helix of the M domain. Examination of the mutant protein's subcellular distribution revealed that it was not localized to the plasma membrane but instead was mistargeted to intracytoplasmic membranes. Specific plasma membrane targeting was restored by the addition of myristate plus a single basic residue, by multiple basic residues, or by the heterologous hydrophobic membrane-binding domain from the cellular Fyn protein. These results suggest that the fourth alpha-helix of the RSV M domain promotes specific targeting of Gag to the plasma membrane, either through a direct interaction with plasma membrane phospholipids or a membrane-associated cellular factor or by maintaining the conformation of Gag to expose specific plasma membrane targeting sequences.

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