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Initiation of Agrobacterium tumefaciens T-DNA processing: purified proteins VirD1 and VirD2 catalyze site- and strand-specific cleavage of superhelical T-border DNA in vitro

Scheiffele, Peter and Pansegrau, W. and Lanka, E.. (1995) Initiation of Agrobacterium tumefaciens T-DNA processing: purified proteins VirD1 and VirD2 catalyze site- and strand-specific cleavage of superhelical T-border DNA in vitro. Journal of Biological Chemistry, 270 (3). pp. 1269-1276.

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Official URL: http://edoc.unibas.ch/dok/A5259871

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Abstract

T-DNA processing during agroinfection of plants is initiated by site- and strand-specific incision at the T-DNA border sequences of the Ti plasmid. Two proteins are required for this reaction: VirD2 (49.6 kDa), catalyzing a site-specific cleaving-joining reaction on single-stranded DNA in vitro (Pansegrau, W., Schoumacher, F., Hohn, B., and Lanka, E. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 11538-11542), and VirD1 (16.1 kDa), an accessory protein required for VirD2-mediated specific cleavage of double-stranded DNA. Following efficient overproduction, VirD1 was isolated in active form from inclusion bodies and purified to near homogeneity. The protein was applied together with purified VirD2 protein for specific cleavage of double-stranded T-DNA border sequences in vitro. The reaction proceeds on negative superhelical DNA and requires Mg2+ ions. Relaxed DNA is not cleaved. The 5' terminus of the broken DNA strand is covalently associated with protein, most probably VirD2, and the cleavage site is located at the same position that is found in vivo, indicating that the in vitro reaction mimics the one that takes place in induced agrobacteria. Relaxation of plasmid DNA occurs only upon addition of protein denaturants, suggesting that the DNA in the VirD1/VirD2 complex is topologically constrained by strong protein-DNA interactions. The characteristics of the VirD1/VirD2-mediated cleavage reaction strongly resemble those observed with relaxosomes of IncP plasmids involved in initiation of transfer DNA replication during bacterial conjugation.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Neurobiology > Cell Biology (Scheiffele)
UniBasel Contributors:Scheiffele, Peter
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:American Society for Biochemistry and Molecular Biology
ISSN:0021-9258
e-ISSN:1083-351X
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:10 Nov 2017 10:41
Deposited On:22 Mar 2012 13:23

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