Disease relevance of O2R_110

• We studied the dynamics of site-specific recombination by the resolvase encoded by the Escherichia coli transposon Tn3 [1].
• The resolvase partially complements the UV and hydroxyurea hypersensitivity and associated aberrant mitoses of an rqh1(-) mutant [2].
• Moreover, the first purification and definitive identification of a telomere resolvase has been reported for phage N15 [3].
• The broad-host-range plasmid pAM beta 1 from Gram-positive bacteria encodes a resolvase, designated Res beta, which shares homology with the proteins of the resolvase-invertase family [4].
• We have purified one of these proteins, 67RuvC, from Lactococcus lactis phage bIL67 and demonstrated that it functions as a Holliday structure resolvase [5].

High impact information on O2R_110

• In vitro recombination by Tn3 resolvase of plasmids containing two directly repeated recombination (res) sites generates two singly interlinked catenated rings [6].
• A putative binding site may be located in the N-terminal portion of the TnpR (resolvase) structural gene sequences [7].
• Examination of the Tn501 DNA sequence also reveals a potential tnpM coding sequence upstream of the Tn501 resolvase gene [7].
• To dissect the pathways of Holliday junction processing in a eukaryote, we have targeted an Escherichia coli Holliday junction resolvase to the nuclei of fission yeast recombination-deficient mutants and analysed their phenotypes [2].
• We conclude that the specificity of recombination is achieved by a three-stage recognition system: binding of resolvase to separate sites, formation of the synaptosome and determination of site orientation from within the complex [8].

Chemical compound and disease context of O2R_110

• Norfloxacin-induced DNA cleavage occurs at the dif resolvase locus in Escherichia coli and is the result of interaction with topoisomerase IV [9].

Biological context of O2R_110

• A 760 base pair nucleotide sequence of transposon Tn1721 containing the resolvase (tnpR) gene has been determined [10].
• The binding sites on these transposons were compared with those in the gamma delta/Tn3 system: the similarities between the two groups of transposons revealed some general features of resolvase-DNA interactions while the differences in fine structure elucidated the specificity of each resolvase [11].
• The dual functions of resolvase, site-specific recombination and the regulation of its own expression from tnpR, both require the interaction of this protein with the DNA sequence at res, but the specificity of this interaction differs between groups of Tn3-like elements [11].
• These experiments showed that each resolvase bound to the same three sites (I, II and III) within res from Tn1721 and to an equivalent series of three sites on Tn21: the differences in the amino acid sequences of the two proteins did not affect their interaction with either DNA [11].
• In this study, DNA fragments that contained res from Tn21 or Tn1721 were subjected to either cleavage by DNase I or methylation by dimethyl sulphate in the presence of the purified resolvase from Tn21 or Tn1721 [11].

Associations of O2R_110 with chemical compounds

• The intermediate accumulates at low reaction temperatures and is stabilized by crosslinking of the resolvase protomers with glutaraldehyde [8].
• Induction of the transcriptional fusions results in production of resolvase, which in turn, catalyzes excision of a linked tetracycline-resistance reporter gene flanked by direct repeats of res, the DNA sequences at which resolvase functions [12].
• The activity of Tn21 resolvase for recombination between each hybrid and a wild-type res site was measured in the presence of CAP and cyclic AMP [13].
• With one exception, where a glutamate residue had been replaced by leucine, the activity of these mutants was similar to that of wild-type Tn21 resolvase [14].
• We propose a model for Tn4451 excision and insertion in which the resolvase/invertase domain of TnpX introduces 2-bp staggered cuts at these GA dinucleotides [15].

Regulatory relationships of O2R_110

• Expression of tnpR under tac promoter control generated sufficient resolvase protein for enzyme purification and for in vitro studies [10].

Other interactions of O2R_110

• Tn1721-encoded resolvase: structure of the tnpR gene and its in vitro functions [10].

Analytical, diagnostic and therapeutic context of O2R_110

• We have isolated in quantitative yield the synaptic intermediate formed during site-specific recombination by Tn3 resolvase and characterized it by restriction endonuclease mapping, electron microscopy and topological methods [8].
• Sequence analysis indicated that the resolvase/invertase domain of TnpX was likely to be involved in the excision process by catalysing the formation of a 2 bp staggered nick on either side of the GA dinucleotide located at the ends of the transposon and at the junction of the circular form [16].
• We used site-directed mutagenesis to investigate such residues in the RusA resolvase [17].
• The solution properties of Tn3 resolvase (Tn3R) were studied by sedimentation equilibrium, sedimentation velocity analytical ultracentrifugation, and small-angle neutron scattering [18].
• We have constructed a genetic bioassay for inhibitors of site-specific recombination by transposon Tn3 resolvase [19].

References