Site-specific integration of foreign DNA into minimal bacterial and human target sequences mediated by a conjugative relaxase. Site-specific integration of foreign DNA into minimal bacterial and human target sequences mediated by a conjugative relaxase. Agúndez L, González-Prieto C, Machón C, Llosa M. PLoS One. 2012;7(1):e31047. doi: 10.1371/journal.pone.0031047. Epub 2012 Jan 23.2012-01-22T23:00:00Z<div style="text-align:justify;"></div><p style="text-align:justify;"><span class="ms-rteThemeFontFace-1 ms-rteFontSize-2"><span class="ms-rteThemeForeColor-2-5 ms-rteThemeFontFace-1 ms-rteFontSize-2" style="font-weight:bold;">Abstract</span><br></span></p><div style="color:#000000;font-family:arial, helvetica, clean, sans-serif;text-align:justify;"><h4 style="margin:0px 0.25em 0px 0px;color:#000000;font-weight:bold;text-transform:uppercase;float:left;"><span class="ms-rteThemeFontFace-1 ms-rteFontSize-2">BACKGROUND: </span></h4><p style="margin-bottom:0.5em;"><span class="ms-rteThemeFontFace-1 ms-rteFontSize-2">Bacterial conjugation is a mechanism for horizontal DNA transfer between bacteria which requires cell to cell contact, usually mediated by self-transmissible plasmids. A protein known as relaxase is responsible for the <span class="highlight ms-rteThemeFontFace-1 ms-rteFontSize-2">processing</span> of DNA during bacterial conjugation. TrwC, the relaxase of conjugative plasmid R388, is also able to catalyze site-specific integration of the transferred DNA into a copy of its target, the origin of transfer (oriT), present in a recipient plasmid. This reaction confers TrwC a high biotechnological potential as a tool for genomic engineering.</span></p><h4 style="margin:0px 0.25em 0px 0px;color:#000000;font-weight:bold;text-transform:uppercase;float:left;"><span class="ms-rteThemeFontFace-1 ms-rteFontSize-2">METHODOLOGY/PRINCIPAL FINDINGS: </span></h4><p style="margin-bottom:0.5em;"><span class="ms-rteThemeFontFace-1 ms-rteFontSize-2">We have characterized this reaction by conjugal mobilization of a suicide plasmid to a recipient cell with an oriT-containing plasmid, selecting for the cointegrates. Proteins TrwA and IHF enhanced integration frequency. TrwC could also catalyze integration when it is expressed from the recipient cell. Both Y18 and Y26 catalytic tyrosil residues were essential to perform the reaction, while TrwC DNA helicase activity was dispensable. The target DNA could be reduced to 17 bp encompassing TrwC nicking and binding sites. Two human genomic sequences resembling the 17 bp segment were accepted as targets for TrwC-mediated site-specific integration. TrwC could also integrate the incoming DNA molecule into an oriT copy present in the recipient chromosome.</span></p><h4 style="margin:0px 0.25em 0px 0px;color:#000000;font-weight:bold;text-transform:uppercase;float:left;"><span class="ms-rteThemeFontFace-1 ms-rteFontSize-2">CONCLUSIONS/SIGNIFICANCE: </span></h4><p style="margin-bottom:0.5em;font-size:1.04em;"><span class="ms-rteThemeFontFace-1 ms-rteFontSize-2">The results support a model for TrwC-mediated site-specific integration. This reaction may allow R388 to integrate into the genome of non-permissive hosts upon conjugative transfer. Also, the ability to act on target sequences present in the human genome underscores the biotechnological potential of conjugative relaxase TrwC as a site-specific integrase for genomic modification of human cells.</span></p></div><p>​<span style="color:#474f51;font-family:"yanone kaffeesatz";font-size:18px;background-color:#ffffff;">[</span><a href="http://www.ncbi.nlm.nih.gov/pubmed/22292089" style="color:#ed391b;margin:0px;padding:0px;border:0px;font-stretch:inherit;font-size:18px;line-height:inherit;font-family:"yanone kaffeesatz";vertical-align:baseline;background-color:#ffffff;">pubmed</a><span style="color:#474f51;font-family:"yanone kaffeesatz";font-size:18px;background-color:#ffffff;">]</span><br></p>131