RESUMO
Replication of the single-stranded DNA genome of plant geminiviruses follows a rolling circle mechanism. It strictly depends on a 'rolling circle replication initiator protein', the M(r) 41 kDa viral Rep protein, encoded by the C1 or AC1 genes. Using wheat dwarf virus (WDV) and tomato yellow leaf curl virus (TYLCV) as examples, we show that not only the full-size Rep proteins, but also a putative 30 kDa translation product of WDV open reading frame C1-N as well as an artificially shortened 24 kDa Rep of TYLCV, cleave and join single-stranded origin DNA in vitro. Thus the pivotal origin recognition and processing activities of geminivirus Rep proteins must be mediated by the amino-terminal domain of Rep.
Assuntos
Replicação do DNA/fisiologia , Geminiviridae/fisiologia , Origem de Replicação/genética , Proteínas Virais/metabolismo , Replicação Viral/fisiologia , Sequência de Aminoácidos , Sequência de Bases , DNA de Cadeia Simples/metabolismo , Genes Virais/genética , Solanum lycopersicum/virologia , Dados de Sequência Molecular , Fases de Leitura Aberta/genética , Polidesoxirribonucleotídeos/metabolismo , Proteínas Recombinantes de Fusão/biossíntese , Triticum/virologia , Proteínas Virais/genéticaRESUMO
Replication of the single-stranded DNA genome of plant geminiviruses follows a rolling circle mechanism. It strictly depends on a 'replication initiator protein' (Rep) which is the sole viral protein essential for replication. Rep protein catalyzes multiple reactions during the reproductive cycle of the virus. Here we summarize the recent advances of in vivo and in vitro analyses of the various Rep protein activities in a model for replication initiation and termination. In addition, the position of the geminivirus Rep protein within a general context of bacterial and mammalian replication initiator proteins is discussed.
