Arabidopsis HAP2/GCS1 is a gamete fusion protein homologous to somatic and viral fusogens.
Valansi, C., Moi, D., Leikina, E., Matveev, E., Grana, M., Chernomordik, L. V., Romero, H., Aguilar, P. S. and Podbilewicz, B.
Department of Biology, Technion- Israel Institute of Technology, Haifa 32000, Israel.
Laboratorio de Biologia Celular de Membranas, Instituto de Investigaciones Biotecnologicas "Dr. Rodolfo A. Ugalde," Universidad Nacional de San Martin, Buenos Aires, CP1650, Argentina.
Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.
Unidad de Bioinformatica, Institut Pasteur Montevideo, Montevideo 11400, Uruguay.
Laboratorio de Organizacion y Evolucion del Genoma, Unidad de Genomica Evolutiva, Departamento Ecologia y Evolucion, Facultad de Ciencias/Centro Universitario Regional del Este, Universidad de la Republica, Montevideo 11400, Uruguay.
Laboratorio de Biologia Celular de Membranas, Instituto de Investigaciones Biotecnologicas "Dr. Rodolfo A. Ugalde," Universidad Nacional de San Martin, Buenos Aires, CP1650, Argentina paguilar@iib.unsam.edu.ar podbilew@technion.ac.il.
Department of Biology, Technion- Israel Institute of Technology, Haifa 32000, Israel paguilar@iib.unsam.edu.ar podbilew@technion.ac.il.
Cell-cell fusion is inherent to sexual reproduction. Loss of HAPLESS 2/GENERATIVE CELL SPECIFIC 1 (HAP2/GCS1) proteins results in gamete fusion failure in diverse organisms, but their exact role is unclear. In this study, we show that Arabidopsis thaliana HAP2/GCS1 is sufficient to promote mammalian cell-cell fusion. Hemifusion and complete fusion depend on HAP2/GCS1 presence in both fusing cells. Furthermore, expression of HAP2 on the surface of pseudotyped vesicular stomatitis virus results in homotypic virus-cell fusion. We demonstrate that the Caenorhabditis elegans Epithelial Fusion Failure 1 (EFF-1) somatic cell fusogen can replace HAP2/GCS1 in one of the fusing membranes, indicating that HAP2/GCS1 and EFF-1 share a similar fusion mechanism. Structural modeling of the HAP2/GCS1 protein family predicts that they are homologous to EFF-1 and viral class II fusion proteins (e.g., Zika virus). We name this superfamily Fusexins: fusion proteins essential for sexual reproduction and exoplasmic merger of plasma membranes. We suggest a common origin and evolution of sexual reproduction, enveloped virus entry into cells, and somatic cell fusion.
Journal of Cell Biology 216(3): 571-581 (2017)