REPETITIVE DNA INSERTION IN A PROTEIN-KINASE ORF OF A LATENT FSV (FELDMANNIA SP. VIRUS) GENOME

We describe the structure of a Feldmannia sp. virus (FsV) genome integ rated in the brown alga, Feldmannia. This integrated FsV genome appear s to be permanently inactivated and lost its ability to excise and rep licate. Unlike the replicated form of FsV, this integrated FsV genome contains a large (>50 kb) repeat region inserted in a protein kinase o pen reading frame. While related to the 173-bp repeats previously char acterized in the FsV genome (Lee et ai., 1995), Southern blot analysis indicates that the repeats in the inactive, integrated FsV genome are distinct from those previously characterized. Fine structural analysi s of the repeat-insertion sites in the protein kinase gene indicates t hat there are 8- and 10-bp palindromic sequences present in multiple l ocations located near the repeat-insertion site. The translated protei n kinase contains all of the catalytic motifs conserved in most serine /threonine protein kinases and a potential autophosphorylation site. T his protein kinase gene is expressed as RNA in sporophyte plants where virus production is active but not in gametophyte plants where the vi rus genome is latent. The structure of the integrated virus genome is discussed, (C) 1998 Academic Press.