title: Molecular characterization of the Rep protein of the blackgram isolate of Indian mungbean yellow mosaic virus.
abstract: The complete nucleotide sequence of the blackgram isolate of mungbean yellow mosaic virus, IMYMV-Bg, which infects legumes in India, was determined and compared at the amino acid level with those of other whitefly-transmitted geminiviruses. The genome organization of IMYMV-Bg was similar to that of the begomoviruses. A unique feature of the genome organization was the sequence divergence of the common region (CR) between DNA-A and DNA-B. In order to understand the mechanism of viral DNA replication, the replication initiator protein, Rep, of IMYMV-Bg was overexpressed in E. coli. The recombinant and refolded Rep bound to CR-sequences of IMYMV-Bg in a specific manner. In this study, evidence is presented for ATP-upregulated cleavage function and ATP-mediated conformational change of Rep. It is hypothesized that, although ATP is not required for cleavage, ATP-mediated conformational changes may result in better access of Rep to the DNA-cleavage site. Evidence is also presented for a site-specific topoisomerase function of Rep, which has not been demonstrated before. The Rep protein can be classified as a type-I topoisomerase because of its nicking activity and sensitivity towards camptothecin, a topoisomerase type-I inhibitor.
authors.affiliation: Plant Molecular Biology, International Centre for Genetic Engineering & Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India1.
authors.forename: V
authors.initials: V
authors.lastname: Pant
authors.affiliation: Plant Molecular Biology, International Centre for Genetic Engineering & Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India1.
authors.forename: D
authors.initials: D
authors.lastname: Gupta
authors.affiliation: Plant Molecular Biology, International Centre for Genetic Engineering & Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India1.
authors.forename: N Roy
authors.initials: NR
authors.lastname: Choudhury
authors.affiliation: Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi 110012, India2.
authors.forename: V G
authors.initials: VG
authors.lastname: Malathi
authors.affiliation: Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi 110012, India2.
authors.forename: A
authors.initials: A
authors.lastname: Varma
authors.affiliation: Plant Molecular Biology, International Centre for Genetic Engineering & Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India1.
authors.forename: S K
authors.initials: SK
authors.lastname: Mukherjee
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D001483:Base Sequence; D003001:Cloning, Molecular; D004265:DNA Helicases / Q000737:chemistry* / Q000378:metabolism; D004264:DNA Topoisomerases, Type I / Q000378:metabolism; D004268:DNA-Binding Proteins; D007887:Fabaceae / Q000821:virology*; D017791:Geminiviridae / Q000235:genetics*; D016679:Genome, Viral; D008969:Molecular Sequence Data; D010946:Plants, Medicinal; D011487:Protein Conformation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000378:metabolism; D015534:Trans-Activators / Q000737:chemistry* / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; C045264:replication initiator protein; D000255:Adenosine Triphosphate; D004265:DNA Helicases; D004264:DNA Topoisomerases, Type I