COAT PROTEIN OF THE ECTOCARPUS-SILICULOSUS VIRUS

Ectocarpus siliculosus virus, EsV, multiplies in sporangia and gametan gia of the marine brown alga Ectocarpus siliculosus. We describe an im proved method for the isolation of morphologically intact and infectio us virus from diseased plants. We show that treatment of virus particl es with high concentrations of CsCl results in a substantial loss of s tructural proteins. One of the proteins which resists CsCl treatment i s glycoprotein-l, the largest of the three viral glycoproteins. We hav e isolated an EsV genomic fragment with an open reading frame encoding glycoprotein-1. The predicted amino acid sequence is rich in hydrophi lic amino acids, but contains hydrophobic regions close to the amino a nd carboxy termini. A discrepancy between the molecular weight predict ed from the coding region and the molecular weight determined by gel e lectrophoresis suggests that proteolytic processing is required for th e maturation of the protein. (C) 1995 academic Press, Inc.