Involvement of Rad52 in T-DNA circle formation during Agrobacterium tumefaciens-mediated transformation of Saccharomyces cerevisiae.
Agrobacterium tumefaciens cells carrying a tumour inducing plasmid (Ti-plasmid) can transfer a defined region of transfer DNA (T-DNA) to plant cells as well as to yeast. This process of Agrobacterium-mediated transformation (AMT) eventually results in the incorporation of the T-DNA in the genomic DNA of the recipient cells. All available evidence indicates that T-strand transfer closely resembles conjugal DNA transfer as found between Gram-negative bacteria. However, where conjugal plasmid DNA transfer starts via relaxase-mediated processing of a single origin of transfer (oriT), the T-DNA is flanked by two imperfect direct border repeats which are both substrates for the Ti-plasmid encoded relaxase VirD2. Yeast was used as a model system to investigate the requirements of the recipient cell for the formation of T-DNA circles after AMT. It was found that, despite the absence of self-homology on the T-DNA, the homologous repair proteins Rad52 and Rad51 are involved in T-DNA circle formation. A model is presented involving the formation of T-DNA concatemers derived from T-strands by a process of strand-transfer catalysed by VirD2. These concatemers are then resolved into T-DNA circles by homologous recombination in the recipient cell.
Department of Molecular and Developmental Genetics, nstitute of Biology Leiden, Leiden, Sylviusweg 72, 2333 BE, The Netherlands.
Martijn
M
Rolloos
Marius H C
MH
Dohmen
Paul J J
PJ
Hooykaas
Bert J
BJ
van der Zaal
D016960:Agrobacterium tumefaciens / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D004270:DNA, Circular / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism; D051721:Rad52 DNA Repair and Recombination Protein / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014170:Transformation, Genetic
D004269:DNA, Bacterial; D004270:DNA, Circular; C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D029701:Saccharomyces cerevisiae Proteins; C036483:T-DNA; C495151:RAD51 protein, S cerevisiae; D051135:Rad51 Recombinase