title: Right-border sequences enable the left border of an Agrobacterium tumefaciens nopaline Ti-plasmid to produce single-stranded DNA.
abstract: The T-region of nopaline-type Ti-plasmids (the portion of the plasmid that is transferred to plant cells) of Agrobacterium tumefaciens is delimited by 23-25 bp direct repeats. They are nicked by the products of the virD locus and the presence of these nicked sites is correlated with the synthesis of single-stranded T-region copies. Despite previous indications to the contrary, we show that the pTiT37 T-region left border is capable of producing single-stranded DNA with high efficiency and that its ability to do so is totally dependent on right border-proximal cis-acting sequences, most probably overdrive, located several kilobases from the border. The absence of overdrive does not affect the single-strand nicking activity of the virD product but only the production of single-stranded copies from the nicked substrate.
authors.affiliation: Department of Agronomy, University of Illinois, 1102 S. Goodwin Avenue, 61801, Urbana, IL, USA.
authors.forename: F A
authors.initials: FA
authors.lastname: Culianez-Macia
authors.forename: A G
authors.initials: AG
authors.lastname: Hepburn