Disease relevance of tnpR

• In order to obtain stable Hfr donor strains of Pseudomonas aeruginosa PAO, we constructed a derivative of an RP1 (ts) plasmid, pME134, which was defective in the resolvase gene (tnpR) of transposon Tn801 [1].
• A set of 68 independent mutations was obtained in Escherichia coli by transposon Tn813 (a tnpR mutant of Tn21)-mediated cointegration with the self-transmissible R388 plasmid [2].
• The SIVET lysogen has a defective H-19B prophage encoding the TnpR resolvase gene downstream of the phage PR promoter and a cat gene with an inserted tet gene flanked by targets for the TnpR resolvase [3].

High impact information on tnpR

• A putative binding site may be located in the N-terminal portion of the TnpR (resolvase) structural gene sequences [4].
• These identified a 120-bp region between the tnpA and tnpR genes that can be subdivided into three separate protein-binding sites [5].
• To extend the utility of the reporter gene fusion approach to such studies, we have constructed a gene expression reporter cassette that permits the generation of transcriptional fusions to tnpR encoding resolvase, a site-specific recombinase of the transposable element gamma delta [6].
• Using this assay, we have determined that (i) tnpR is not required for immunity, (ii) only the terminal 38 base pairs of Tn3 need be present to confer immunity, and (iii) other parts of Tn3 appear not to confer immunity [7].
• The amino acid sequences of Gin, Pin, Hin, and TnpR are compared, and the evolutionary relationship between these prokaryotic site-specific recombination systems is discussed [8].

Biological context of tnpR

• The gamma delta resolvase, product of the transposon's tnpR gene, mediates a site-specific recombination between two copies of gamma delta directly repeated on the same replicon [9].
• Like the tnpR- repeats, the Tn3 #2 repeats occur at both junctions between the parental plasmids, and are associated with a 5-bp direct duplication of the pHS1 target site [10].
• The nucleotide sequences of Tn1 and Tn2 were determined over a 1,195-base-pair segment constituting most of the sequences of the tnpR and bla genes and the intervening region [11].
• Three other ORFs, 2, 3 and 5, potentially encode proteins which are similar in size to the resolvase protein encoded by the Tn3 gene tnpR; however, none of the protein products deduced from these ORF share extensive aa sequence identity with other resolvase proteins [12].
• RESULTS: Plasmid pFPTB1 contains a complete Tn3-like transposon of 4950 bp consisting of the left terminal repeat, Tn3-related tnpR and tnpA genes for transposition functions, a novel gene for ampicillin resistance bla(TEM-135), and the right terminal repeat [13].

Associations of tnpR with chemical compounds

• Both tnpR and res are present in IRa, while the tnpR gene of IRb is interrupted by the insertion of an IS26 insertion element [14].
• Tn1739tnpR is a derivative of Tn1721 with a chloramphenicol-resistance-encoding gene (CmR), the lambda cI repressor gene, and a further copy of the resolvase-encoding tnpR gene under control of the tac promoter [15].

Physical interactions of tnpR

• The tnpR promoter had 40% of lac promoter efficiency its activity being autoregulated by binding of resolvase to res, as shown by fusion to the galactokinase gene [16].

Regulatory relationships of tnpR

• Expression of tnpR under tac promoter control generated sufficient resolvase protein for enzyme purification and for in vitro studies [17].

Other interactions of tnpR

• In order to determine the extent of the res site we have constructed in vitro a series of deletions that terminate within the tnpA-tnpR intergenic region, and have analyzed their effect on site-specific recombination [9].
• We also examined the ability of various transposons, assumed to be closely related, to complement the tnpA and tnpR mutations of Tn2603 [18].
• Tn1721-encoded resolvase: structure of the tnpR gene and its in vitro functions [17].
• However, in all three transposons, and in contrast to Tn3, the tnpR gene is transcribed towards tnpA gene, and the res site is upstream of both [19].

References