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VirD4‐independent transformation by CloDF13 evidences an unknown factor required for the genetic colonization of plants via Agrobacterium
Author(s) -
Escudero Jesús,
Den DulkRas Amke,
RegensburgTuïnk Tonny J. G.,
Hooykaas Paul J. J.
Publication year - 2003
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2003.03328.x
Subject(s) - biology , agrobacterium , transformation (genetics) , virulence , yeast , plasmid , dna , genetics , horizontal gene transfer , host (biology) , virulence factor , saccharomyces cerevisiae , gene , genome
Summary Agrobacteriumuses a mechanism similar to conjugation fortrans‐kingdom transfer of its oncogenic T‐DNA. A defined VirB/VirD4 Type IV secretion system is responsible for such a genetic transfer. In addition, certain virulence proteins as VirE2 can be mobilized into host cells by the same apparatus. VirE2 is essential to achieve plant but not yeast transformation. We found that the limited host range plasmid CloDF13 can be recruited by the virulence apparatus ofAgrobacteriumfor transfer to eukaryotic hosts. As expected the VirB transport complex was required for suchtrans‐kingdom DNA transfer. However, unexpectedly, the coupling factor VirD4 turned out to be necessary for transfer to plants but not for transport into yeast. The CloDF13 encoded coupling factor (Mob) was essential for transfer to both plants and yeast though. This is interpreted by the different specificities of Mob and VirD4. Hence, Mob being required for the transport of the CloDF13 transferred DNA (to both plants and yeast) and VirD4 being required for transport of virulence proteins such as VirE2. Nevertheless, the presence of the VirE2 protein in the host plant was not sufficient to restore the deficiency for VirD4 in the transforming bacteria. We propose that Mob functions encoded by the plasmid CloDF13 are sufficient for DNA mobilization to eukaryotic cells but that the VirD4‐mediated pathway is essential to achieve DNA nuclear establishment specifically in plants. This suggests that otherAgrobacterium virulence proteins besides VirE2 are translocated and essential for plant transformation.