Genetic analysis of heptad-repeat regions in the G2 fusion subunit of the Junín arenavirus envelope glycoprotein

• Autores: York, Joanne; Agnihothram, Sudhakar S.; Romanowski, Víctor; Nunberg, Jack H.
• Año de publicación: 2005
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Bioquímica; Arenavirus; Envelope glycoprotein; GP-C; Junín virus or Argentine hemorrhagic fever virus; Membrane fusion; Mutagenesis; Six-helix bundle
• Institución: Universidad Nacional de La Plata

The G2 fusion subunit of the Junín virus envelope glycoprotein GP-C contains two hydrophobic heptad-repeat regions that are postulated to form a six-helix bundle structure required for the membrane fusion activity of Class I viral fusion proteins. We have investigated the role of these heptad-repeat regions and, specifically, the importance of the putative interhelical a and d position sidechains by using alanine-scanning mutagenesis. All the mutant glycoproteins were expressed and transported to the cell surface. Proteolytic maturation at the subtilisin kexin isozyme-1/site-1-protease (SKI-1/S1P) cleavage site was observed in all but two of the mutants. Among the adequately cleaved mutant glycoproteins, four positions in the N-terminal region (I333, L336, L347 and L350) and two positions in the C-terminal region (R392 and W395) were shown to be important determinants of cell-cell fusion. Taken together, our results indicate that α-helical coiled-coil structures are likely critical in promoting arenavirus membrane fusion. These findings support the inclusion of the arenavirus GP-C among the Class I viral fusion proteins and suggest pharmacologic and immunologic strategies for targeting arenavirus infection and hemorrhagic fever.
Instituto de Biotecnologia y Biologia Molecular