title: The N-terminal heptad repeat region of reovirus cell attachment protein sigma 1 is responsible for sigma 1 oligomer stability and possesses intrinsic oligomerization function.
abstract: The oligomerization domain of the reovirus cell attachment protein (sigma 1) was probed using the type 3 reovirus sigma 1 synthesized in vitro. Trypsin cleaved the sigma 1 protein (49K molecular weight) approximately in the middle and yielded a 26K N-terminal fragment and a 23K C-terminal fragment. Under conditions which allowed for the identification of intact sigma 1 in the oligomeric form (approximately 200K) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the N-terminal 26K fragment was found to exist as stable trimers (80K) and, to a less extent, as dimers (54K), whereas the C-terminal fragment remained in the monomeric form. A polypeptide (161 amino acids) containing the N-terminal heptad repeat region synthesized in vitro was capable of forming stable dimers and trimers. Using various criteria, we demonstrated that the stability of the intact sigma 1 oligomer is conferred mainly by the N-terminal heptad repeat region. Our results are summarized in a model in which individual heptad repeats are held together in a three-stranded alpha-helical coiled-coil structure via both hydrophobic and electrostatic interactions.
authors.affiliation: Department of Microbiology and Infectious Diseases, University of Calgary Health Sciences Centre, Alberta, Canada.
authors.forename: G
authors.initials: G
authors.lastname: Leone
authors.forename: R
authors.initials: R
authors.lastname: Duncan
authors.forename: D C
authors.initials: DC
authors.lastname: Mah
authors.forename: A
authors.initials: A
authors.lastname: Price
authors.forename: L W
authors.initials: LW
authors.lastname: Cashdollar
authors.forename: P W
authors.initials: PW
authors.lastname: Lee
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D036022:Capsid Proteins; D003001:Cloning, Molecular; D004229:Dithiothreitol; D007477:Ions; D046911:Macromolecular Substances; D008623:Mercaptoethanol; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009841:Oligonucleotides / Q000737:chemistry; D011485:Protein Binding; D012087:Reoviridae / Q000032:analysis*; D013329:Structure-Activity Relationship; D014357:Trypsin / Q000494:pharmacology; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics
chemical_list: D036022:Capsid Proteins; D007477:Ions; D046911:Macromolecular Substances; D009841:Oligonucleotides; D014764:Viral Proteins; C031728:sigma 1 protein, reovirus; D008623:Mercaptoethanol; D014357:Trypsin; D004229:Dithiothreitol