Abstract
The product of the uvp1 gene of the R46 plasmid, a member of the DNA invertase-resolvase family, was studied to characterize its recombination activity on the R46 plasmid. The purified Uvp1 protein specifically binds to a 256-bp DNA fragment located immediately upstream of the uvp1 gene itself, and overlapping the 5′-conserved segment (5′-CS) of the R46 integron In1. We identified on this fragment a putative resolution (res) site. Using an in vitro assay, we demonstrated the ability of the protein to resolve a synthetic cointegrate containing a direct repeat of the res site. In vivo, we obtained cointegrate resolution in Uvp1-expressing recA − cells. Sites I and II, subsites of the putative res site, lie within the outer boundary of the integron 5′-CS which is common to all the known integrons. Furthermore, a 69-bp DNA element (containing site I) is required for cointegrate resolution. We propose that this recombination mechanism protects R46 plasmid against unequal distribution following fusion with either identical or different integron-bearing plasmids. Moreover, Uvp1 might have a role in generating gene cassette diversity between the two conserved segments of the integron.
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Received: 17 July 1997 / Accepted: 18 December 1997
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Tosini, F., Venanzi, S., Boschi, A. et al. The uvp1 gene on the R46 plasmid encodes a resolvase that catalyzes site-specific resolution involving the 5′-conserved segment of the adjacent integron In1. Mol Gen Genet 258, 404–411 (1998). https://doi.org/10.1007/s004380050748
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DOI: https://doi.org/10.1007/s004380050748