Short report

Identification of the hASCT2-binding domain of the Env ERVWE1/syncytin-1 fusogenic glycoprotein

Valérie Cheynet, Guy Oriol and François Mallet^*

• * Corresponding author: François Mallet francois.mallet@ens-lyon.fr

Author Affiliations

UMR 2714 CNRS-bioMérieux, IFR128 BioSciences Lyon-Gerland, Ecole Normale Supérieure de Lyon, 69364 Lyon Cedex 07, France

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Retrovirology 2006, 3:41 doi:10.1186/1742-4690-3-41

Published: 4 July 2006

Abstract

The cellular HERV-W envelope/syncytin-1 protein, encoded by the envelope gene of the ERVWE1 proviral locus is a fusogenic glycoprotein probably involved in the formation of the placental syncytiotrophoblast layer. Syncytin-1-induced in vitro cell-cell fusion is dependent on the interaction with hASCT2. As no receptor binding domain has been clearly defined in the SU of neither the HERV-W Env nor the retroviruses of the same interference group, we designed an in vitro binding assay to evaluate the interaction of the HERV-W envelope with the hASCT2 receptor. Using truncated HERV-W SU subunits, a region consisting of the N-terminal 124 amino acids of the mature SU glycoprotein was determined as the minimal receptor-binding domain. This domain contains several sub-domains which are poorly conserved among retroviruses of this interference group but a region of 18 residus containing the SDGGGX₂DX₂R conserved motif was proved to be essential for syncytin-1-hASCT2 interaction.