scholarly journals Addition of carbohydrate side chains at novel sites on influenza virus hemagglutinin can modulate the folding, transport, and activity of the molecule.

1988 ◽  
Vol 107 (6) ◽  
pp. 2059-2073 ◽  
Author(s):  
P Gallagher ◽  
J Henneberry ◽  
I Wilson ◽  
J Sambrook ◽  
M J Gething
Keyword(s):  
Influenza Virus ◽  
Intracellular Transport ◽  
Secretory Pathway ◽  
High Efficiency ◽  
Biological Activities ◽  
Side Chains ◽  
Wild Type ◽  
Temperature Dependent ◽  
Influenza Virus Hemagglutinin ◽  
General Tool

We have constructed and expressed a series of mutant influenza virus hemagglutinins, each containing a new consensus site for glycosylation in addition to the seven sites found on the wild-type protein. Oligosaccharide side chains were added with high efficiency at four of the five novel sites, located on areas of the protein's surface that are not normally shielded by carbohydrate. Investigations of the structure, intracellular transport, and biological activities of the mutant hemagglutinin molecules indicated that (a) supernumerary carbohydrate side chains can be used to shield or disrupt functional epitopes on the surface of hemagglutinin, and (b) the presence of an additional oligosaccharide may cause temperature-dependent defects in the transport of the glycoprotein. We discuss the addition of supernumerary oligosaccharides as a general tool for shielding chosen areas of the surface of proteins that enter or traverse the secretory pathway.

scholarly journals New Insights into the Spring-Loaded Conformational Change of Influenza Virus Hemagglutinin

2002 ◽  
Vol 76 (9) ◽  
pp. 4456-4466 ◽  
Author(s):  
Jennifer A. Gruenke ◽  
R. Todd Armstrong ◽  
William W. Newcomb ◽  
Jay C. Brown ◽  
Judith M. White
Keyword(s):  
Influenza Virus ◽  
Conformational Change ◽  
Conformational Changes ◽  
Limited Proteolysis ◽  
Coiled Coil ◽  
Fusion Peptide ◽  
Wild Type ◽  
Influenza Virus Hemagglutinin ◽  
Target Membrane ◽  
Mutant Forms

ABSTRACT Influenza virus hemagglutinin undergoes a conformational change in which a loop-to-helix “spring-loaded” conformational change forms a coiled coil that positions the fusion peptide for interaction with the target bilayer. Previous work has shown that two proline mutations designed to disrupt this change disrupt fusion but did not determine the basis for the fusion defect. In this work, we made six additional mutants with single proline substitutions in the region that undergoes the spring-loaded conformational change and two additional mutants with double proline substitutions in this region. All double mutants were fusion inactive. We analyzed one double mutant, F63P/F70P, as an example. We observed that F63P/F70P undergoes key low-pH-induced conformational changes and binds tightly to target membranes. However, limited proteolysis and electron microscopy observations showed that the mutant forms a coiled coil that is only ∼50% the length of the wild type, suggesting that it is splayed in its N-terminal half. This work further supports the hypothesis that the spring-loaded conformational change is necessary for fusion. Our data also indicate that the spring-loaded conformational change has another role beyond presenting the fusion peptide to the target membrane.

Mutants of the influenza virus hemagglutinin with a block in intracellular transport exhibit impaired trimer assembly

1988 ◽  
Vol 11 ◽  
pp. 19
Author(s):  
Christiane Will ◽  
Kazumichi Kuroda ◽  
Wolfgang Garten ◽  
Hans-Dieter Klenk
Keyword(s):  
Influenza Virus ◽  
Intracellular Transport ◽  
Influenza Virus Hemagglutinin

Peramivir analogues bearing hydrophilic side chains exhibit higher activities against H275Y mutant than wild-type influenza virus

2017 ◽  
Vol 15 (46) ◽  
pp. 9910-9922 ◽  
Author(s):  
Din-Chi Chiu ◽  
Tzu-Chen Lin ◽  
Wen-I Huang ◽  
Ting-Jen Cheng ◽  
Keng-Chang Tsai ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Side Chain ◽  
Side Chains ◽  
Wild Type

The peramivir analogue bearing a hydrophilic glycerol side chain displays 9-fold stronger inhibition against H275Y mutant than wild-type influenza virus.

scholarly journals Amino Acid Sequence Requirements of the Transmembrane and Cytoplasmic Domains of Influenza Virus Hemagglutinin for Viable Membrane Fusion

1999 ◽  
Vol 10 (6) ◽  
pp. 1821-1836 ◽  
Author(s):  
Grigory B. Melikyan ◽  
Sasa Lin ◽  
Michael G. Roth ◽  
Fredric S. Cohen
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Membrane Fusion ◽  
Integral Membrane Protein ◽  
Wild Type ◽  
Influenza Virus Hemagglutinin ◽  
Tm Domain ◽  
Fusion Pores ◽  
Sequence Requirements

The amino acid sequence requirements of the transmembrane (TM) domain and cytoplasmic tail (CT) of the hemagglutinin (HA) of influenza virus in membrane fusion have been investigated. Fusion properties of wild-type HA were compared with those of chimeras consisting of the ectodomain of HA and the TM domain and/or CT of polyimmunoglobulin receptor, a nonviral integral membrane protein. The presence of a CT was not required for fusion. But when a TM domain and CT were present, fusion activity was greater when they were derived from the same protein than derived from different proteins. In fact, the chimera with a TM domain of HA and truncated CT of polyimmunoglobulin receptor did not support full fusion, indicating that the two regions are not functionally independent. Despite the fact that there is wide latitude in the sequence of the TM domain that supports fusion, a point mutation of a semiconserved residue within the TM domain of HA inhibited fusion. The ability of a foreign TM domain to support fusion contradicts the hypothesis that a pore is composed solely of fusion proteins and supports the theory that the TM domain creates fusion pores after a stage of hemifusion has been achieved.

scholarly journals Disulfide bond formation during the folding of influenza virus hemagglutinin.

1992 ◽  
Vol 118 (2) ◽  
pp. 227-244 ◽  
Author(s):  
M S Segal ◽  
J M Bye ◽  
J F Sambrook ◽  
M J Gething
Keyword(s):  
Influenza Virus ◽  
Disulfide Bonds ◽  
Intracellular Transport ◽  
Cellular Protein ◽  
Cysteine Residues ◽  
Mutant Proteins ◽  
Influenza Virus Hemagglutinin ◽  
Stalk Domain ◽  
Do So

To study the importance of individual sulfhydryl residues during the folding and assembly in vivo of influenza virus hemagglutinin (HA), we have constructed and expressed a series of mutant HA proteins in which cysteines involved in three disulfide bonds have been substituted by serine residues. Investigations of the structure and intracellular transport of the mutant proteins indicate that (a) cysteine residues in the ectodomain are essential both for efficient folding of HA and for stabilization of the folded molecule; (b) cysteine residues in the globular portion of the ectodomain are likely to form native disulfide bonds rapidly and directly, without involvement of intermediate, nonnative linkages; and (c) cysteine residues in the stalk portion of the ectodomain also appear not to form intermediate disulfide bonds, even though they have the opportunity to do so, being separated from their correct partners by hundreds of amino acids including two or more other sulfhydryl residues. We propose a role for the cellular protein BiP in shielding the cysteine residues of the stalk domain during the folding process, thus preventing them from forming intermediate, nonnative disulfide bonds.

scholarly journals Intracellular Transport, Assembly, and Degradation of Wild-Type and Disease-linked Mutant Gap Junction Proteins

2000 ◽  
Vol 11 (6) ◽  
pp. 1933-1946 ◽  
Author(s):  
Judy K. VanSlyke ◽  
Suzanne M. Deschenes ◽  
Linda S. Musil
Keyword(s):  
Gap Junction ◽  
Intracellular Transport ◽  
Secretory Pathway ◽  
Proteasome Inhibitors ◽  
Wild Type ◽  
Plasma Membrane Protein ◽  
Charcot Marie Tooth Disease ◽  
Nonionic Detergent ◽  
Tooth Disease ◽  
Junction Proteins

More than 130 different mutations in the gap junction integral plasma membrane protein connexin32 (Cx32) have been linked to the human peripheral neuropathy X-linked Charcot–Marie–Tooth disease (CMTX). How these various mutants are processed by the cell and the mechanism(s) by which they cause CMTX are unknown. To address these issues, we have studied the intracellular transport, assembly, and degradation of three CMTX-linked Cx32 mutants stably expressed in PC12 cells. Each mutant had a distinct fate: E208K Cx32 appeared to be retained in the endoplasmic reticulum (ER), whereas both the E186K and R142W mutants were transported to perinuclear compartments from which they trafficked either to lysosomes (R142W Cx32) or back to the ER (E186K Cx32). Despite these differences, each mutant was soluble in nonionic detergent but unable to assemble into homomeric connexons. Degradation of both mutant and wild-type connexins was rapid (t1/2 < 3 h) and took place at least in part in the ER by a process sensitive to proteasome inhibitors. The mutants studied are therefore unlikely to cause disease by accumulating in degradation-resistant aggregates but instead are efficiently cleared from the cell by quality control processes that prevent abnormal connexin molecules from traversing the secretory pathway.

scholarly journals Effect of the Addition of Oligosaccharides on the Biological Activities and Antigenicity of Influenza A/H3N2 Virus Hemagglutinin

2004 ◽  
Vol 78 (18) ◽  
pp. 9605-9611 ◽  
Author(s):  
Yasuhiro Abe ◽  
Emi Takashita ◽  
Kanetsu Sugawara ◽  
Yoko Matsuzaki ◽  
Yasushi Muraki ◽  
...  
Keyword(s):  
Cell Fusion ◽  
Receptor Binding ◽  
Influenza A ◽  
Intracellular Transport ◽  
Biological Activities ◽  
Site Directed Mutagenesis ◽  
H3n2 Virus ◽  
Wild Type ◽  
Glycosylation Sites ◽  
Globular Head

ABSTRACT Influenza A/H3N2 viruses have developed an increased number of glycosylation sites on the globular head of the hemagglutinin (HA) protein since their appearance in 1968. Here, the effect of addition of oligosaccharide chains to the HA of A/H3N2 viruses on its biological activities was investigated. We constructed seven mutant HAs of A/Aichi/2/68 virus with one to six glycosylation sites on the globular head, as found in natural isolates, by site-directed mutagenesis and analyzed their intracellular transport, receptor binding, and cell fusion activities. The glycosylation sites of mutant HAs correspond to representative A/H3N2 isolates (A/Victoria/3/75, A/Memphis/6/86, or A/Sydney/5/97). The results showed that all the mutant HAs were transported to the cell surface as efficiently as wild-type HA. Although mutant HAs containing three to six glycosylation sites decreased receptor binding activity, their cell fusion activity was not affected. The reactivity of mutant HAs having four to six glycosylation sites with human sera collected in 1976 was much lower than that of wild-type HA. Thus, the addition of new oligosaccharides to the globular head of the HA of A/H3N2 viruses may have provided the virus with an ability to evade antibody pressures by changing antigenicity without an unacceptable defect in biological activity.

scholarly journals Differential extractability of influenza virus hemagglutinin during intracellular transport in polarized epithelial cells and nonpolar fibroblasts.

1989 ◽  
Vol 108 (3) ◽  
pp. 821-832 ◽  
Author(s):  
J E Skibbens ◽  
M G Roth ◽  
K S Matlin
Keyword(s):  
Influenza Virus ◽  
Plasma Membrane ◽  
Epithelial Cells ◽  
Disulfide Bond ◽  
Intracellular Transport ◽  
Mdck Cells ◽  
Apical Plasma Membrane ◽  
Transport Pathway ◽  
Influenza Virus Hemagglutinin ◽  
Triton X

Biochemical changes in the influenza virus hemagglutinin during intracellular transport to the apical plasma membrane of epithelial cells were investigated in Madin-Darby canine kidney (MDCK) cells and in LLC-PK1 cells stably transfected with a hemagglutinin gene. After pulse-labeling a substantial fraction of hemagglutinin was observed to become insoluble in isotonic solutions of Triton X-100. Insolubility of hemagglutinin was detected late in the transport pathway after addition of complex sugars in the Golgi complex but before insertion of the protein in the plasma membrane. Insolubility was not dependent on oligosaccharide modification since deoxymannojirimycin (dMM), which inhibits mannose trimming, failed to prevent its onset. Insolubility was not due to assembly of virus particles at the plasma membrane because insoluble hemagglutinin was also observed in transfected cells. Hemagglutinin insolubility was also seen in MDCK cells cultured in suspension and in chick embryo fibroblasts, indicating that insolubility and plasma membrane polarity are not simply correlated. In addition to insolubility, an apparent transport-dependent reduction of the disulfide bond linking HA1 and HA2 in hemagglutinin was detected. Because of the timing of both insolubility and the loss of the disulfide bond, these modifications may be important in the delivery of the hemagglutinin to the cell surface.

scholarly journals Modification of the Cytoplasmic Domain of Influenza Virus Hemagglutinin Affects Enlargement of the Fusion Pore

2000 ◽  
Vol 74 (16) ◽  
pp. 7529-7537 ◽  
Author(s):  
Christine Kozerski ◽  
Evgeni Ponimaskin ◽  
Britta Schroth-Diez ◽  
Michael F. G. Schmidt ◽  
Andreas Herrmann
Keyword(s):  
Influenza Virus ◽  
Membrane Fusion ◽  
Transmembrane Domain ◽  
Expression System ◽  
Fusion Pore ◽  
Target Cells ◽  
Fusion Activity ◽  
Wild Type ◽  
Influenza Virus Hemagglutinin ◽  
Pore Enlargement

ABSTRACT The fusion activity of chimeras of influenza virus hemagglutinin (HA) (from A/fpv/Rostock/34; subtype H7) with the transmembrane domain (TM) and/or cytoplasmic tail (CT) either from the nonviral, nonfusogenic T-cell surface protein CD4 or from the fusogenic Sendai virus F-protein was studied. Wild-type or chimeric HA was expressed in CV-1 cells by the transient T7-RNA-polymerase vaccinia virus expression system. Subsequently, the fusion activity of the expression products was monitored with red blood cells or ghosts as target cells. To assess the different steps of fusion, target cells were labeled with the fluorescent membrane label octadecyl rhodamine B-chloride (R18) (membrane fusion) and with the cytoplasmic fluorophores calcein (molecular weight [MW], 623; formation of small aqueous fusion pore) and tetramethylrhodamine-dextran (MW, 10,000; enlargement of fusion pore). All chimeric HA/F-proteins, as well as the chimera with the TM of CD4 and the CT of HA, were able to mediate the different steps of fusion very similarly to wild-type HA. Quite differently, chimeric proteins with the CT of CD4 were strongly impaired in mediating pore enlargement. However, membrane fusion and formation of small pores were similar to those of wild-type HA, indicating that the conformational change of the ectodomain and earlier fusion steps were not inhibited. Various properties of the CT which may affect pore enlargement are considered. We surmise that the hydrophobicity of the sequence adjacent to the transmembrane domain is important for pore dilation.

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