Identification of sequence elements regulating promoter activity and replication of a monopartite begomovirus-associated DNA β satellite

• Published in: Journal of general virology 2009, Vol.90 (Pt 1), p.253-260
• Main Authors: Eini, Omid, Behjatnia, S.A. Akbar, Dogra, Satish, Dry, Ian B, Randles, John W, Rezaian, M. Ali
• Format: Article
• Language: English
• Subjects: Artificial Gene Fusion; Base Sequence; Begomovirus; Begomovirus - physiology; beta-glucuronidase; Binding Sites; Cotton leaf curl Multan virus; DNA Replication; DNA, Satellite - biosynthesis; DNA, Satellite - genetics; G-box motif; Geminiviridae; gene expression; Genes, Reporter; Glucuronidase - biosynthesis; Glucuronidase - genetics; Host-Pathogen Interactions; Molecular Sequence Data; mutation; Nicotiana - virology; Nicotiana tabacum; Plant Diseases - virology; promoter regions; Promoter Regions, Genetic; Protein Binding; reporter genes; satellite DNA; Sequence Deletion; tobacco; Transcription, Genetic
• ISSN: 0022-1317; 1465-2099
• DOI: 10.1099/vir.0.002980-0

DNA β is a circular single-stranded satellite DNA associated with certain monopartite begomoviruses (family Geminiviridae) which causes economically important diseases such as cotton leaf curl disease. DNA β contains a single gene, βC1, which encodes a pathogenicity protein responsible for symptom production. Transient expression studies in Nicotiana tabacum using the β-glucuronidase reporter gene driven by a βC1 promoter-deletion series of the DNA β associated with cotton leaf curl Multan virus identified a 68 nt region (between -139 and -207) which is important for βC1 transcription. This 68 nt region contains a G-box (CACGTG) located 143 nt upstream of the βC1 start codon. Mutation of the G-box resulted in a significant reduction in βC1 promoter activity and DNA β replication efficiency. In addition, the G-box motif was found to bind specifically to a protein(s) in nuclear extracts prepared from tobacco leaf tissues. Our results indicate that interaction of the G-box motif with host nuclear factors is important for efficient gene expression and replication of DNA β.