title: Disulfide bond formation during the folding of influenza virus hemagglutinin.
abstract: 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.
authors.affiliation: Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235.
authors.forename: M S
authors.initials: MS
authors.lastname: Segal
authors.forename: J M
authors.initials: JM
authors.lastname: Bye
authors.forename: J F
authors.initials: JF
authors.lastname: Sambrook
authors.forename: M J
authors.initials: MJ
authors.lastname: Gething
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D002460:Cell Line; D003001:Cloning, Molecular; D004220:Disulfides / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D006389:Hemagglutinins, Viral / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D011487:Protein Conformation; D013539:Simian virus 40 / Q000235:genetics; D014162:Transfection; D014759:Viral Envelope Proteins / Q000378:metabolism
chemical_list: D004220:Disulfides; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D006389:Hemagglutinins, Viral; D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D014759:Viral Envelope Proteins