title: A proapoptotic peptide derived from reovirus outer capsid protein {micro}1 has membrane-destabilizing activity.
abstract: The reovirus outer capsid protein μ1 is responsible for cell membrane penetration during virus entry and contains determinants necessary for virus-induced apoptosis. Residues 582 to 611 of μ1 are necessary and sufficient for reovirus-induced apoptosis, and residues 594 and 595 independently regulate the efficiency of viral entry and reovirus-induced cell apoptosis, respectively. Two of three α-helices within this region, helix 1 (residues 582 to 611) and helix 3 (residues 644 to 675), play a role in reovirus-induced apoptosis. Here, we chemically synthesized peptides representing helix 1 (H1), H1:K594D, H1:I595K, and helix 3 (H3) and examined their biological properties. We found that H1, but not H3, was able to cause concentration- and size-dependent leakage of molecules from small unilamellar liposomes. We further found that direct application of H1, but not H1:K594D, H1:I595K, or H3, to cells resulted in cytotoxicity. Application of the H1 peptide to L929 cells caused rapid elevations in intracellular calcium concentration that were independent of phospholipase C activation. Cytotoxicity of H1 was not restricted to eukaryotic cells, as the H1 peptide also had bactericidal activity. Based on these findings, we propose that the proapoptotic function of the H1 region of μ1 is dependent on its capacity to destabilize cellular membranes and cause release of molecules from intracellular organelles that ultimately induces cell necrosis or apoptosis, depending on the dose.
authors.affiliation: Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Hungerford Hill Road, Ithaca, New York 14853, USA.
authors.forename: Jae-Won
authors.initials: JW
authors.lastname: Kim
authors.forename: Sangbom M
authors.initials: SM
authors.lastname: Lyi
authors.forename: Colin R
authors.initials: CR
authors.lastname: Parrish
authors.forename: John S L
authors.initials: JS
authors.lastname: Parker
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D016466:CHO Cells; D036022:Capsid Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects* / Q000821:virology; D002463:Cell Membrane Permeability; D002942:Circular Dichroism; D006224:Cricetinae; D003412:Cricetulus; D004912:Erythrocytes / Q000502:physiology; D006461:Hemolysis; D007739:L Cells; D008081:Liposomes / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D030102:Orthoreovirus, Mammalian / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology
chemical_list: D036022:Capsid Proteins; D008081:Liposomes; D010455:Peptides; C055356:mu1 protein, Reovirus