<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Griffith, Kevin L</style></author><author><style face="normal" font="default" size="100%">Wolf, Richard E</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Genetic evidence for pre-recruitment as the mechanism of transcription activation by SoxS of Escherichia coli: the dominance of DNA binding mutations of SoxS.</style></title><secondary-title><style face="normal" font="default" size="100%">J Mol Biol</style></secondary-title><alt-title><style face="normal" font="default" size="100%">J. Mol. Biol.</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Base Sequence</style></keyword><keyword><style  face="normal" font="default" size="100%">Binding Sites</style></keyword><keyword><style  face="normal" font="default" size="100%">DNA, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Escherichia coli</style></keyword><keyword><style  face="normal" font="default" size="100%">Escherichia coli Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Gene Expression Regulation, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Genes, Bacterial</style></keyword><keyword><style  face="normal" font="default" size="100%">Genes, Dominant</style></keyword><keyword><style  face="normal" font="default" size="100%">Mutation</style></keyword><keyword><style  face="normal" font="default" size="100%">Regulon</style></keyword><keyword><style  face="normal" font="default" size="100%">Trans-Activators</style></keyword><keyword><style  face="normal" font="default" size="100%">Transcriptional Activation</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2004</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2004 Nov 12</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">344</style></volume><pages><style face="normal" font="default" size="100%">1-10</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">SoxS, the direct transcriptional activator of the Escherichia coli superoxide (SoxRS) regulon, displays several unusual characteristics which suggest that it is unlikely to activate transcription by the ususal recruitment mechanism. Thus, agents that generate superoxide endogenously and thereby provoke the defense response elicit the de novo synthesis of SoxS, and with the SoxS binding site being highly degenerate, the number of SoxS binding sites per cell far exceeds the number of SoxS molecules per cell. To account for these distinctive features of the SoxRS system, we proposed &quot;pre-recruitment&quot; as the mechanism by which SoxS activates transcription of the regulon's genes. In pre-recruitment, newly synthesized SoxS molecules form binary complexes with RNA polymerase in solution. These complexes provide the information content to allow the 2500 molecules of SoxS per cell to scan the 65,000 SoxS binding sites per cell for the 200 binding sites per cell that reside within SoxS-dependent promoters. As a test of whether SoxS activates transcription by recruitment or pre-recruitment, we determined the dominance relationships of SoxS mutations conferring defective DNA binding. We found that soxS DNA binding mutations are dominant to the wild-type allele, a result consistent with the pre-recruitment hypothesis, but opposite to that expected for an activator that functions by recruitment. Moreover, whereas positive control mutations of activators functioning by recruitment are usually dominant, a soxS positive control mutation was not. Lastly, with the SoxRS system as an example, we discuss the physiological requirement for stringent regulation of transcriptional activators that function by pre-recruitment.</style></abstract><issue><style face="normal" font="default" size="100%">1</style></issue><custom1><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/15504398?dopt=Abstract</style></custom1></record></records></xml>