The conjugal intermediate of plasmid RSF1010 inhibits Agrobacterium tumefaciens virulence and VirB-dependent export of VirE2.
Agrobacterium tumefaciens causes crown gall disease by transferring oncogenic, single-stranded DNA (T strand), covalently attached to the VirD2 protein, across the bacterial envelope into plant cells where its expression results in tumor formation. The single-stranded DNA binding protein VirE2 is also transferred into the plant cell, though the location at which VirE2 interacts with the T strand is still under investigation. The movement of the transferred DNA and VirE2 from A. tumefaciens to the plant cell depends on the membrane-localized VirB and VirD4 proteins. Further, the movement of the IncQ broad-host-range plasmid RSF1010 between Agrobacterium strains or from Agrobacterium to plants also requires the virB-encoded transfer system. Our earlier studies showed that the presence of the RSF1010 plasmid in wild-type strains of Agrobacterium inhibits both their virulence and their capacity to transport VirE2, as assayed by coinfection with virE mutants. Here we demonstrate that the capacity to form a conjugal intermediate of RSF1010 is necessary for this inhibition, suggesting that the transferred form of the plasmid competes with the VirD2-T strand and/or VirE2 for a common export site.
Stahl
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Plant Science Institute, Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania.
Jacobs
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Binns
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D016960:Agrobacterium tumefaciens / Q000235:genetics* / Q000472:pathogenicity*; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000378:metabolism*; D001483:Base Sequence; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D007473:Ion Channels; D010944:Plants / Q000382:microbiology; D011815:R Factors; D018741:Replication Origin; D014157:Transcription Factors / Q000378:metabolism; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D007473:Ion Channels; C036483:T-DNA; D014157:Transcription Factors; D037521:Virulence Factors; C095754:mobA protein, E coli; C051583:virE2 protein, Agrobacterium