Rab11 Binding Promotes the p14 FAST Protein-Induced Syncytium Formation.

Reptile reoviruses encode the p14 fusion-associated small transmembrane (FAST) protein, which induces cell-cell membrane fusion as a nonstructural protein. When the virus enters the host cell, the p14 protein is encoded, synthesized, and delivered to the plasma membrane via the endoplasmic reticulum-Golgi transport system. During this process, the polybasic motif (PBM) at the proximal membrane terminal of the p14 cytosolic endodomain interacts with Rab11 on the Golgi. This interaction places p14 into vesicles enclosed by the AP-1 adaptor, transporting it to the plasma membrane and causing membrane fusion. In this study, we used the surface plasmon resonance principle to confirm that p14 had a substantial affinity for Rab11 at the membrane, and we also proved at the cellular level that Rab11 directly increased p14-induced syncytium formation and improved membrane fusion efficiency. We also found preliminary evidence that p14 could act as a fusion peptide to trigger liposome-cell fusion.