The Polar Region Consecutive to the HIV Fusion Peptide Participates in Membrane Fusion†

Biochemistry ◽  
2000 ◽  
Vol 39 (7) ◽  
pp. 1826-1833 ◽  
Author(s):  
Sergio Gerardo Peisajovich ◽  
Raquel F. Epand ◽  
Moshe Pritsker ◽  
Yechiel Shai ◽  
Richard M. Epand
Keyword(s):  
Membrane Fusion ◽  
Polar Region ◽  
Fusion Peptide

scholarly journals Novel Mutations That Control the Sphingolipid and Cholesterol Dependence of the Semliki Forest Virus Fusion Protein

2002 ◽  
Vol 76 (24) ◽  
pp. 12712-12722 ◽  
Author(s):  
Prodyot K. Chatterjee ◽  
Christina H. Eng ◽  
Margaret Kielian
Keyword(s):  
Membrane Fusion ◽  
Semliki Forest Virus ◽  
Fusion Reaction ◽  
Fusion Peptide ◽  
Single Amino Acid ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Novel Mutations ◽  
E1 Protein ◽  
Target Membrane

ABSTRACT The enveloped alphavirus Semliki Forest virus (SFV) infects cells via a membrane fusion reaction mediated by the E1 membrane protein. Efficient SFV-membrane fusion requires the presence of cholesterol and sphingolipid in the target membrane. Here we report on two mutants, srf-4 and srf-5, selected for growth in cholesterol-depleted cells. Like the previously isolated srf-3 mutant (E1 proline 226 to serine), the phenotypes of the srf-4 and srf-5 mutants were conferred by single-amino-acid changes in the E1 protein: leucine 44 to phenylalanine and valine 178 to alanine, respectively. Like srf-3, srf-4 and srf-5 show striking increases in the cholesterol independence of growth, infection, membrane fusion, and exit. Unexpectedly, and unlike srf-3, srf-4 and srf-5 showed highly efficient fusion with sphingolipid-free membranes in both lipid- and content-mixing assays. Both srf-4 and srf-5 formed E1 homotrimers of decreased stability compared to the homotrimers of the wild type and the srf-3 mutant. All three srf mutations lie in the same domain of E1, but the srf-4 and srf-5 mutations are spatially separated from srf-3. When expressed together, the three mutations could interact to produce increased sterol independence and to cause temperature-sensitive E1 transport. Thus, the srf-4 and srf-5 mutations identify novel regions of E1 that are distinct from the fusion peptide and srf-3 region and modulate the requirements for both sphingolipid and cholesterol in virus-membrane fusion.

scholarly journals Charged N-terminus of Influenza Fusion Peptide Facilitates Membrane Fusion

2018 ◽  
Vol 19 (2) ◽  
pp. 578 ◽  
Author(s):  
Remigiusz Worch ◽  
Anita Dudek ◽  
Joanna Krupa ◽  
Anna Szymaniec ◽  
Piotr Setny
Keyword(s):  
Membrane Fusion ◽  
Fusion Peptide ◽  
N Terminus

scholarly journals Sequence elements of the fusion peptide of human respiratory syncytial virus fusion protein required for activity

2006 ◽  
Vol 87 (6) ◽  
pp. 1649-1658 ◽  
Author(s):  
Diana Martín ◽  
Lesley J. Calder ◽  
Blanca García-Barreno ◽  
John J. Skehel ◽  
José A. Melero
Keyword(s):  
Respiratory Syncytial Virus ◽  
Membrane Fusion ◽  
Conformational Changes ◽  
Fusion Peptide ◽  
Human Respiratory Syncytial Virus ◽  
Full Length ◽  
Fusion Peptides ◽  
Sequence Elements ◽  
Syncytial Virus ◽  
Simple Molecules

We have reported previously the expression and purification of an anchorless form of the human respiratory syncytial virus (HRSV) F protein () representing the ectodomain of the full-length F. molecules are seen as unaggregated cones by electron microscopy but completion of proteolytic cleavage of the F0 monomers in the trimer leads to a change in shape from cones to lollipops that aggregate into rosettes. This aggregation apparently occurs by interaction of the fusion peptides of molecules that are exposed after cleavage. Since exposure of the fusion peptide is a key event in the process of membrane fusion, changes associated with cleavage may reflect those occurring in full-length F during membrane fusion. Deletions or substitutions that changed either the length, charge or hydrophobicity of the fusion peptide inhibited aggregation of , and these mutants remained as unaggregated cones after cleavage. In contrast, more conservative changes did not inhibit the change of shape and aggregation of . When the same changes were introduced in the fusion peptide of full-length F, only the mutations that inhibited aggregation of prevented membrane fusion. Thus, the conformational changes that follow completion of cleavage of the protein require a functional fusion peptide. These sequence constraints may restrict accumulation of sequence changes in the fusion peptide of HRSV F when compared with other hydrophobic regions of the molecule.

scholarly journals Membrane Structures of the Hemifusion-Inducing Fusion Peptide Mutant G1S and theFusion-Blocking Mutant G1V of Influenza Virus HemagglutininSuggest a Mechanism for Pore Opening in MembraneFusion

2005 ◽  
Vol 79 (18) ◽  
pp. 12065-12076 ◽  
Author(s):  
Yinling Li ◽  
Xing Han ◽  
Alex L. Lai ◽  
John H. Bushweller ◽  
David S. Cafiso ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Membrane Fusion ◽  
Lipid Bilayer ◽  
Membrane Surface ◽  
Helical Structure ◽  
Fusion Peptide ◽  
Membrane Structures ◽  
Influenza Virus Hemagglutinin ◽  
Target Membrane ◽  
Pore Opening

ABSTRACT Influenza virus hemagglutinin (HA)-mediated membrane fusion is initiated by a conformational change that releases a V-shaped hydrophobic fusion domain, the fusion peptide, into the lipid bilayer of the target membrane. The most N-terminal residue of this domain, a glycine, is highly conserved and is particularly critical for HA function; G1S and G1V mutant HAs cause hemifusion and abolish fusion, respectively. We have determined the atomic resolution structures of the G1S and G1V mutant fusion domains in membrane environments. G1S forms a V with a disrupted “glycine edge” on its N-terminal arm and G1V adopts a slightly tilted linear helical structure in membranes. Abolishment of the kink in G1V results in reduced hydrophobic penetration of the lipid bilayer and an increased propensity to formβ -structures at the membrane surface. These results underline the functional importance of the kink in the fusion peptide and suggest a structural role for the N-terminal glycine ridge in viral membrane fusion.

scholarly journals An Epitope of the Semliki Forest Virus Fusion Protein Exposed during Virus-Membrane Fusion

1999 ◽  
Vol 73 (12) ◽  
pp. 10029-10039 ◽  
Author(s):  
Anna Ahn ◽  
Matthew R. Klimjack ◽  
Prodyot K. Chatterjee ◽  
Margaret Kielian
Keyword(s):  
Membrane Fusion ◽  
Binding Site ◽  
Semliki Forest Virus ◽  
Fusion Reaction ◽  
Ph Dependence ◽  
Fusion Peptide ◽  
Endocytic Pathway ◽  
Spike Protein ◽  
Viral Fusion ◽  
Wide Range

ABSTRACT Semliki Forest virus (SFV) is an enveloped alphavirus that infects cells via a membrane fusion reaction triggered by acidic pH in the endocytic pathway. Fusion is mediated by the spike protein E1 subunit, an integral membrane protein that contains the viral fusion peptide and forms a stable homotrimer during fusion. We have characterized four monoclonal antibodies (MAbs) specific for the acid conformation of E1. These MAbs did not inhibit fusion, suggesting that they bind to an E1 region different from the fusion peptide. Competition analyses demonstrated that all four MAbs bound to spatially related sites on acid-treated virions or isolated spike proteins. To map the binding site, we selected for virus mutants resistant to one of the MAbs, E1a-1. One virus isolate, SFV 4-2, showed reduced binding of three acid-specific MAbs including E1a-1, while its binding of one acid-specific MAb as well as non-acid-specific MAbs to E1 and E2 was unchanged. The SFV 4-2 mutant was fully infectious, formed the E1 homotrimer, and had the wild-type pH dependence of infection. Sequence analysis demonstrated that the relevant mutation in SFV 4-2 was a change of E1 glycine 157 to arginine (G157R). Decreased binding of MAb E1a-1 was observed under a wide range of assay conditions, strongly suggesting that the E1 G157R mutation directly affects the MAb binding site. These data thus localize an E1 region that is normally hidden in the neutral pH structure and becomes exposed as part of the reorganization of the spike protein to its fusion-active conformation.

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