title: Interaction with a host ubiquitin-conjugating enzyme is required for the pathogenicity of a geminiviral DNA beta satellite.
abstract: DNA beta is a single-stranded satellite DNA which encodes a single gene, betaC1. To better understand the role of betaC1 in the pathogenicity of DNA beta, a yeast two-hybrid screen of a tomato cDNA library was carried out using betaC1 from Cotton leaf curl Multan virus (CLCuMV) DNA beta as the bait. A ubiquitin-conjugating enzyme, designated SlUBC3, which functionally complemented a yeast mutant deficient in ubiquitin-conjugating enzymes was identified. The authenticity and specificity of the interaction between betaC1 and SlUBC3 was confirmed both in vivo, using a bimolecular fluorescence complementation assay, and in vitro, using a protein-binding assay. Analysis of deletion mutants of the betaC1 protein showed that a myristoylation-like motif is required both for its interaction with SlUBC3 and the induction of DNA-beta-specific symptoms in host plants. The level of polyubiquitinated proteins in transgenic tobacco plants expressing betaC1 was found to be reduced compared with wild-type plants. These results are consistent with the hypothesis that interaction of betaC1 with SlUBC3 is required for DNA-beta-specific symptom induction, and that this is possibly due to downregulation of the host ubiquitin proteasome pathway.
authors.affiliation: School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, SA 5064, Australia. omid.einigandomani@adelaide.edu.au
authors.forename: Omid
authors.initials: O
authors.lastname: Eini
authors.forename: Satish
authors.initials: S
authors.lastname: Dogra
authors.forename: Luke A
authors.initials: LA
authors.lastname: Selth
authors.forename: Ian B
authors.initials: IB
authors.lastname: Dry
authors.forename: John W
authors.initials: JW
authors.lastname: Randles
authors.forename: M Ali
authors.initials: MA
authors.lastname: Rezaian
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D004276:DNA, Satellite / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D004279:DNA, Viral / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D017791:Geminiviridae / Q000235:genetics / Q000472:pathogenicity*; D015723:Gene Library; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000378:metabolism*; D016415:Sequence Alignment; D013379:Substrate Specificity; D020798:Two-Hybrid System Techniques; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D004276:DNA, Satellite; D004279:DNA, Viral; D010940:Plant Proteins; D044763:Ubiquitin-Conjugating Enzymes