A potassium channel protein encoded by chlorella virus PBCV-1

The Large chlorella virus PBCV-1, which contains double-stranded DNA (dsDNA ), encodes a 94-codon open reading frame (ORF) that contains a motif resemb ling the signature sequence of the pore domain of potassium channel protein s. Phylogenetic analyses of the encoded protein, Kcv, indicate a previously unidentified type of potassium channel. The messenger RNA encoded by the O RF Leads to functional expression of a potassium-selective conductance in X enopus laevis oocytes. The channel blockers amantadine and barium, but not cesium, inhibit this conductance, in addition to virus plaque formation. Th us, PBCV-1 encodes the first known viral protein that functions as a potass ium-selective channel and is essential in the virus Life cycle.