Arenavirus Stable Signal Peptide Is the Keystone Subunit for Glycoprotein Complex Organization

Bederka, Lydia H.; Bonhomme, Cyrille J.; Ling, Emily L.; Buchmeier, Michael J.

Functional insertion of the HA epitope within the signal peptide region of the LCMV glycoprotein was further confirmed by the ability of the signal peptide to retain its interaction with the GP2 subunit, as determined by immunoprecipitation studies. We confirmed this SSP-GP2 interaction, as Schrempf et al. detected the signal peptide via GP2 pulldown experiments (34) . Insertion of the FLLL double point mutations within the HA SSP GPC construct was detrimental to GPC expression, although single point mutations within this motif were tolerated. These mutations, while allowing SSP to retain its association with the transmembrane-spanning GP2 subunit, obstructed the interaction with the remaining extracellular spike GP1 subunit.