Structure and membrane interaction of the internal fusion peptide of avian sarcoma leukosis virus

Cheng, Shu‐Fang; Wu, Chengwei; Kantchev, Eric Assen B.; Chang, Ding‐Kwo

doi:10.1111/j.1432-1033.2004.04436.x

Cited by 17 publications

(15 citation statements)

References 38 publications

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“…The 16-residue FP of avian sarcoma/ leukosis virus also appears to be helical and may be presented within a 35-residue disulfide-stabilized order-turn-order structure (40,41). The internal FPs of all of the class II enveloped virus fusion proteins are also presented at the tips of elongated, disulfide-stabilized structures composed of anti-parallel ␤-strands (42)(43)(44), whereas the FPs of the class III enveloped virus fusion proteins, such as the vesicular stomatitis virus G protein, are composed of two 10 -11-residue flexible loops contained at the tips of three elongated ␤-strands that are stabilized by disulfide bonds (45,46).…”

Section: Discussionmentioning

confidence: 99%

Features of a Spatially Constrained Cystine Loop in the p10 FAST Protein Ectodomain Define a New Class of Viral Fusion Peptides

Barry¹,

Key²,

Haddad³

et al. 2010

Journal of Biological Chemistry

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The reovirus fusion-associated small transmembrane (FAST) proteins are the smallest known viral membrane fusion proteins. With ectodomains of only ϳ20 -40 residues, it is unclear how such diminutive fusion proteins can mediate cell-cell fusion and syncytium formation. Contained within the 40-residue ectodomain of the p10 FAST protein resides an 11-residue sequence of moderately apolar residues, termed the hydrophobic patch (HP). Previous studies indicate the p10 HP shares operational features with the fusion peptide motifs found within the enveloped virus membrane fusion proteins. Using biotinylation assays, we now report that two highly conserved cysteine residues flanking the p10 HP form an essential intramolecular disulfide bond to create a cystine loop. Mutagenic analyses revealed that both formation of the cystine loop and p10 membrane fusion activity are highly sensitive to changes in the size and spatial arrangement of amino acids within the loop. The p10 cystine loop may therefore function as a cystine noose, where fusion peptide activity is dependent on structural constraints within the noose that force solvent exposure of key hydrophobic residues. Moreover, inhibitors of cell surface thioreductase activity indicate that disruption of the disulfide bridge is important for p10-mediated membrane fusion. This is the first example of a viral fusion peptide composed of a small, spatially constrained cystine loop whose function is dependent on altered loop formation, and it suggests the p10 cystine loop represents a new class of viral fusion peptides.Membrane fusion is an essential process involved in an abundance of biological events, including sperm-egg fusion, multinucleated myotube formation, exocytosis, and enveloped virus entry (1). The fusion reaction is catalyzed by specialized membrane fusion proteins designed to alter bilayer structure and bring about membrane merger. The membrane fusion proteins of various enveloped viruses represent some of the best characterized examples of such fusion catalysts (2). Detailed structural and functional analysis of diverse enveloped virus membrane fusion proteins reveals a common pathway of protein-mediated membrane fusion. Triggered exposure of a hydrophobic fusion peptide (FP), 3 normally sequestered within the complex pre-fusion ectodomain structure of these proteins, results in FP insertion into the donor and/or target membranes. Subsequent structural remodeling of these large ectodomains generates a trimeric hairpin structure that draws the two membranes together, driving lipid mixing (also referred to as hemifusion) and pore formation and expansion (3, 4). Despite a wealth of information, the precise mechanisms by which FPs and conformational remodeling of enveloped virus fusion proteins mediate lipid bilayer rearrangement and fusion remain unclear.The reovirus fusion-associated small transmembrane (FAST) proteins are a singular family of viral membrane fusion proteins. Although many nonenveloped viruses encode proteins involved in membrane permeabilization (...

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Section: Discussionmentioning

confidence: 99%

Features of a Spatially Constrained Cystine Loop in the p10 FAST Protein Ectodomain Define a New Class of Viral Fusion Peptides

Barry¹,

Key²,

Haddad³

et al. 2010

Journal of Biological Chemistry

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“…Structural and membrane interaction properties of a synthetic peptide containing a portion of the wild-type ASLV(A) fusion peptide region (TM residues 17 to 43) have been described by Cheng et al (4). In an aqueous environment, this synthetic ASLV fusion peptide has a beta-sheet structure N-terminal to P29, a slight kink in the structure around P29, and an alpha-helical structure C-terminal to P29.…”

Section: Vol 83 2009 Rescue Of Aslv Tm Function 8583mentioning

confidence: 99%

“…The ASLV fusion region Cterminal to P29 is embedded more deeply than the N-terminal region, the reverse of the HA N-terminal fusion peptide interaction with a membrane. At a low pH, the synthetic ASLV peptide lies deeper in the membrane, possibly facilitating the membrane disruption necessary for the lipid mixing process leading to fusion pores, although the kinked region still resides near the membrane-water interface (4). The flexibility of the fusion peptide kinked region centered on P29 has previously been shown to be critical: mutant ASLV TM glycoproteins with replacements of P29 with amino acids predicted to restrict flexibility resulted in the loss of fusion activity (7).…”

Section: Vol 83 2009 Rescue Of Aslv Tm Function 8583mentioning

confidence: 99%

A Charged Second-Site Mutation in the Fusion Peptide Rescues Replication of a Mutant Avian Sarcoma and Leukosis Virus Lacking Critical Cysteine Residues Flanking the Internal Fusion Domain

Melder

Yin

Delos

et al. 2009

J Virol

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The entry process of the avian sarcoma and leukosis virus (ASLV) family of retroviruses requires first a specific interaction between the viral surface (SU) glycoproteins and a receptor on the cell surface at a neutral pH, triggering conformational changes in the viral SU and transmembrane (TM) glycoproteins, followed by exposure to low pH to complete fusion. The ASLV TM glycoprotein has been proposed to adopt a structure similar to that of the Ebola virus GP2 protein: each contains an internal fusion peptide flanked by cysteine residues predicted to be in a disulfide bond. In a previous study, we concluded that the cysteines flanking the internal fusion peptide in ASLV TM are critical for efficient function of the ASLV viral glycoproteins in mediating entry. In this study, replication-competent ASLV mutant subgroup A [ASLV(A)] variants with these cysteine residues mutated were constructed and genetically selected for improved replication capacity in chicken fibroblasts. Viruses with single cysteine-to-serine mutations reverted to the wild-type sequence. However, viruses with both C9S and C45S (C9,45S) mutations retained both mutations and acquired a second-site mutation that significantly improved the infectivity of the genetically selected virus population. A chargedamino-acid second-site substitution in the TM internal fusion peptide at position 30 is preferred to rescue the C9,45S mutant ASLV(A). ASLV(A) envelope glycoproteins that contain the C9,45S and G30R mutations bind the Tva receptor at wild-type levels and have improved abilities to trigger conformational changes and to form stable TM oligomers compared to those of the C9,45S mutant glycoprotein.All retroviruses have envelope glycoproteins that interact with a receptor protein on the cell surface to initiate entry (18,36). The viral glycoprotein is synthesized as a precursor polyprotein consisting of the surface (SU) glycoprotein, which contains the domains that bind with the cellular receptor, and the transmembrane (TM) glycoprotein, which tethers the protein to the viral surface and contains the domains responsible for fusion of the viral and cellular membranes (32). After synthesis, the precursor viral glycoproteins form trimers through the interaction of the TM domains. The SU and TM domains are then cleaved by a cellular protease, forming a mature, metastable complex capable of mediating viral entry. A specific receptor protein interaction with the SU domain of the mature Env is required to initiate a conformational change in the trimer, separating the globular SU domains to allow the TM glycoproteins to form a structure that projects the fusion peptide toward the target membrane. Two domains in TM, the N-terminal heptad repeat and the C-terminal heptad repeat, are critical for the formation of the extended structure (13, 31)}. The fusion peptide is thought to interact with a target membrane irreversibly, forming an extended prehairpin TM oligomer structure anchored in both the viral and target membranes (35). The cooperation of several of these...

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“…Further studies are necessary to investigate the significance of these mutations on the ability of CR-1986 causing osteopetrosis. Of particular interest are two mutations, one located in the transmembrane domain of gp37 (L158S), and the second located in the membrane fusion peptide (L35S) (6). The fusion peptide of ALSV known as internal fusion peptide (IFP) is a region within the TM protein that is crucial for binding and destabilizing target membranes (8).…”

Section: Discussionmentioning

confidence: 99%

Forensic Investigation of a 1986 Outbreak of Osteopetrosis in Commercial Brown Layers Reveals a Novel Avian Leukosis Virus–Related Genome

Barbosa

Ramírez

Hafner³

et al. 2010

Avian Diseases

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Avian leukosis virus (ALV) is known to cause several neoplastic conditions in chickens, such as B-cell lymphomas, myelocytomas, erythroblastosis, and other types of neoplasia including osteopetrosis. We describe herein the identification of unique ALV-related proviral DNA sequences in an archived chicken bone affected with osteopetrosis. The osteopetrotic bone was obtained from an affected 46-week-old brown layer during an outbreak of osteopetrosis in Costa Rica in 1986. Analysis of proviral DNA in the 23-year-old osteopetrotic bone revealed unique exogenous ALV-related sequences that were named CR-1986 (Costa Rica, 1986). The 5' and 3' long terminal repeats (LTR) in the proviral DNA were identical to each other. The U3 regions in the LTRs were most similar to equivalent sequences in ALV-J, while U5 was identical to known endogenous ALV-E sequences. The predicted CR-1986 envelope protein was most similar to the envelope of myeloblastosis associated virus type 1 (MAV-1), although the percentage of amino acid sequence similarity to MAV-1 was low (90.4%). The variable and hypervariable regions of gp85 displayed several mutations compared to representative strains of ALV. The gp37 (transmembrane or TM) envelope protein showed three leucine to serine mutations that may represent important changes in the conformation of this protein, a finding that is currently being investigated. Several recombination events may have contributed to the emergence of CR-1986 because each analyzed segment was similar to a different ALV. CR-1986 may represent a unique ALV based on distinctive characteristics of its predicted envelope protein in comparison to previously reported ALVs.

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Structure and membrane interaction of the internal fusion peptide of avian sarcoma leukosis virus

Cited by 17 publications

References 38 publications

Features of a Spatially Constrained Cystine Loop in the p10 FAST Protein Ectodomain Define a New Class of Viral Fusion Peptides

Features of a Spatially Constrained Cystine Loop in the p10 FAST Protein Ectodomain Define a New Class of Viral Fusion Peptides

A Charged Second-Site Mutation in the Fusion Peptide Rescues Replication of a Mutant Avian Sarcoma and Leukosis Virus Lacking Critical Cysteine Residues Flanking the Internal Fusion Domain

Forensic Investigation of a 1986 Outbreak of Osteopetrosis in Commercial Brown Layers Reveals a Novel Avian Leukosis Virus–Related Genome

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