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oai:riubu.ubu.es:10259/83762024-01-18T01:05:24Zcom_10259_4862com_10259_5086com_10259_2604col_10259_4863

Ayllón Barasoain, Juan Villar, Enrique Muñoz Barroso, Isabel 2024-01-17T13:06:30Z 2024-01-17T13:06:30Z 2010-01 0022-538X http://hdl.handle.net/10259/8376 10.1128/jvi.01473-09 1098-5514 The entry of enveloped viruses into host cells is preceded by membrane fusion, which in paramyxoviruses is triggered by the fusion (F) protein. Refolding of the F protein from a metastable conformation to a highly stable postfusion form is critical for the promotion of fusion, although the mechanism is still not well understood. Here we examined the effects of mutations of individual residues of the F protein of Newcastle disease virus, located at critical regions of the protein, such as the C terminus of the N-terminal heptad repeat (HRA) and the N terminus of the C-terminal heptad repeat (HRB). Seven of the mutants were expressed at the cell surface, showing differences in antibody reactivity in comparison with the F wild type. The N211A, L461A, I463A, and I463F mutants showed a hyperfusogenic phenotype both in syncytium and in dye transfer assays. The four mutants promoted fusion more efficiently at lower temperatures than the wild type did, meaning they probably had lower energy requirements for activation. Moreover, the N211A, I463A, and I463F mutants exhibited hemagglutinin-neuraminidase (HN)-independent activity when influenza virus hemagglutinin (HA) was coexpressed as an attachment protein. The data are discussed in terms of alterations of the refolding pathway and/or the stability of the prefusion and fusion conformations. This work was partially supported by grants from Junta de Castilla y León (SA009A08) to I.M.-B. and from Fondo de Investigaciones Sanitarias (FIS) (PI08/1813) to E.V. J.A. is a predoctoral fellowship holder from the Spanish Ministerio de Educacio´n, Cultura y Deportes (FPU program; AP-2004-6065). We thank Adolfo García-Sastre for providing anti-HN and polyclonal anti-NDV. Thanks are also due to N. Skinner for language corrections. application/pdf eng American Society for Microbiology Journal of Virology. 2010, V. 84, n. 2, p. 1066-1075 https://doi.org/10.1128/jvi.01473-09 Bioquímica Biología molecular Biochemistry Molecular biology Mutations in the Ectodomain of Newcastle Disease Virus Fusion Protein Confer a Hemagglutinin-Neuraminidase-Independent Phenotype info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion info:eu-repo/semantics/openAccess Journal of Virology 84 2 1066 1075