A novel potassium channel encoded by Ectocarpus siliculosus virus

Kcv, the first identified viral potassium channel encoded by the green algae Paramecium bursaria chlorella virus (PBCV-1), conducted K+ selective currents when expressed in heterologous systems. This K+ channel was proposed to be important for PBCV-1 infection and replication. In the present study, we identified and functionally characterized a novel K+ channel Kesv, encoded by Ectocarpus siliculosus virus that infects filamentous marine brown algae. Kesv encodes a protein of 124 amino acids and is 21.8% identical and 37.1% homologous to Kcv. Membrane topology programs predicted that Kesv consists of three transmembrane domains. When expressed in Xenopus oocytes, Kesv induced largely instantaneous, K+ selective currents that were sensitive to block by Ba2+ and amantadine. Thus, Kesv along with Kcv, constitutes an emerging family of viral potassium channels, which may play important roles in the life cycle of viruses.