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J. Bacteriol., 07 1995, 3758-3763, Vol 177, No. 13
J Perez-Martin and V de Lorenzo
In the presence of toluene and xylenes, the sigma 54-dependent Ps promoter
of the TOL (toluene biodegradation) plasmid pWW0 of Pseudomonas putida is
activated at a distance by the XylR protein, of the NtrC family of
transcriptional regulators. Since contacts between XylR bound to upstream
activating sites and the RNA polymerase require the looping out of the
intervening DNA segment, the intrinsic curvature, the bendability of the
corresponding sequence, and the spatial effects of protein-induced DNA
bending have an influence on promoter activity. Unlike other sigma
54-dependent promoters, Ps does not require the structural aid of the
integration host factor to assemble a specific promoter geometry required
for transcriptional initiation. In vivo analysis of transcriptional
activity in various genetic backgrounds suggests, instead, that the looping
out of intervening DNA sequences in Ps would result from the exacerbation
of a preexisting static bend within the region, assisted by the
histone-like protein HU.
Copyright © 1995, American Society for Microbiology
The sigma 54-dependent promoter Ps of the TOL plasmid of Pseudomonas putida requires HU for transcriptional activation in vivo by XylR
Centro de Investigaciones Biologicas, Consejo Superior de Investigaciones Cientificas, Madrid, Spain.
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