title: Interaction between geminivirus replication protein and the SUMO-conjugating enzyme is required for viral infection.
abstract: Geminiviruses are small DNA viruses that replicate in nuclei of infected plant cells by using plant DNA polymerases. These viruses encode a protein designated AL1, Rep, or AC1 that is essential for viral replication. AL1 is an oligomeric protein that binds to double-stranded DNA, catalyzes the cleavage and ligation of single-stranded DNA, and induces the accumulation of host replication machinery. It also interacts with several host proteins, including the cell cycle regulator retinoblastoma-related protein (RBR), the DNA replication protein PCNA (proliferating cellular nuclear antigen), and the sumoylation enzyme that conjugates SUMO to target proteins (SUMO-conjugating enzyme [SCE1]). The SCE1-binding motif was mapped by deletion to a region encompassing AL1 amino acids 85 to 114. Alanine mutagenesis of lysine residues in the binding region either reduced or eliminated the interaction with SCE1, but no defects were observed for other AL1 functions, such as oligomerization, DNA binding, DNA cleavage, and interaction with AL3 or RBR. The lysine mutations reduced or abolished virus infectivity in plants and viral DNA accumulation in transient-replication assays, suggesting that the AL1-SCE1 interaction is required for viral DNA replication. Ectopic AL1 expression did not result in broad changes in the sumoylation pattern of plant cells, but specific changes were detected, indicating that AL1 modifies the sumoylation state of selected host proteins. These results established the importance of AL1-SCE1 interactions during geminivirus infection of plants and suggested that AL1 alters the sumoylation of selected host factors to create an environment suitable for viral infection.
authors.affiliation: Dept. Biología Celular, Genética y Fisiología, Universidad de Málaga, Campus Teatinos, Málaga, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Sánchez-Durán
authors.forename: Mary B
authors.initials: MB
authors.lastname: Dallas
authors.forename: José T
authors.initials: JT
authors.lastname: Ascencio-Ibañez
authors.forename: Maria Ines
authors.initials: MI
authors.lastname: Reyes
authors.forename: Manuel
authors.initials: M
authors.lastname: Arroyo-Mateos
authors.forename: Javier
authors.initials: J
authors.lastname: Ruiz-Albert
authors.forename: Linda
authors.initials: L
authors.lastname: Hanley-Bowdoin
authors.forename: Eduardo R
authors.initials: ER
authors.lastname: Bejarano
mesh_terms: D019943:Amino Acid Substitution; D001665:Binding Sites; D004252:DNA Mutational Analysis; D017791:Geminiviridae / Q000472:pathogenicity*; D054884:Host-Pathogen Interactions; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017384:Sequence Deletion; D014026:Nicotiana / Q000821:virology*; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C095136:AC1 protein, geminivirus; D050505:Mutant Proteins; D014764:Viral Proteins; D044763:Ubiquitin-Conjugating Enzymes