Geminivirus DNA replication

Geminiviruses are DNA viruses which infect plants. They:have a small genome and encode only a few proteins. Therefore, their DNA replication cycle rel ies largely on the use of cellular DNA replication proteins. The strategy u sed by geminiviruses to replicate their single-stranded DNA (ssDNA) genome consists of a-first stage of conversion of ssDNA into double-stranded DNA ( dsDNA) intermediates and, then, the use of dsDNA as a template to amplify v iral dsDNA: and to produce mature ssDNA genomes by a rolling-circle replica tion mechanism. In addition, the accumulating evidence indicates that viral DNA replication is somehow coupled to the cell cycle regulatory network of the infected cell. For these reasons, geminiviruses are excellent model sy stems to understand the regulation:of DNA replication and cell cycle in pla nt cells. Recent years have witnessed significant progress in the identific ation of cis-acting signals and their interaction with trans-acting factors that contribute to geminivirus origin function. These and other aspects of the geminivirus DNA replication cycle will be reviewed.