Agrobacterium may delay plant nonhomologous end-joining DNA repair via XRCC4 to favor T-DNA integration.
Agrobacterium tumefaciens is a soilborne pathogen that causes crown gall disease in many dicotyledonous plants by transfer of a portion of its tumor-inducing plasmid (T-DNA) into the plant genome. Several plant factors that play a role in Agrobacterium attachment to plant cells and transport of T-DNA to the nucleus have been identified, but the T-DNA integration step during transformation is poorly understood and has been proposed to occur via nonhomologous end-joining (NHEJ)-mediated double-strand DNA break (DSB) repair. Here, we report a negative role of X-ray cross complementation group4 (XRCC4), one of the key proteins required for NHEJ, in Agrobacterium T-DNA integration. Downregulation of XRCC4 in Arabidopsis and Nicotiana benthamiana increased stable transformation due to increased T-DNA integration. Overexpression of XRCC4 in Arabidopsis decreased stable transformation due to decreased T-DNA integration. Interestingly, XRCC4 directly interacted with Agrobacterium protein VirE2 in a yeast two-hybrid system and in planta. VirE2-expressing Arabidopsis plants were more susceptible to the DNA damaging chemical bleomycin and showed increased stable transformation. We hypothesize that VirE2 titrates or excludes active XRCC4 protein available for DSB repair, thus delaying the closure of DSBs in the chromosome, providing greater opportunity for T-DNA to integrate.
Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401, USA.
Zarir E
ZE
Vaghchhipawala
Balaji
B
Vasudevan
Seonghee
S
Lee
Mustafa R
MR
Morsy
Kirankumar S
KS
Mysore
D016960:Agrobacterium tumefaciens / Q000235:genetics*; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D001426:Bacterial Proteins / Q000378:metabolism; D001761:Bleomycin / Q000494:pharmacology; D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair; D004260:DNA Repair; D004269:DNA, Bacterial / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D015536:Down-Regulation; D020868:Gene Silencing; D018745:Genome, Plant; D007473:Ion Channels / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D014170:Transformation, Genetic
D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D007473:Ion Channels; D010940:Plant Proteins; C581740:XRCC4 protein, Arabidopsis; C051583:virE2 protein, Agrobacterium; D001761:Bleomycin