Alternate SlyA and H-NS nucleoprotein complexes control hlyE expression in Escherichia coli K-12.

@article{SlyAHNScontrolhlyE, abstract = {Haemolysin E is a cytolytic pore-forming toxin found in several Escherichia coli and Salmonella enterica strains. Expression of hlyE is repressed by the global regulator H-NS (histone-like nucleoid structuring protein), but can be activated by the regulator SlyA. Expression of a chromosomal hlyE-lacZ fusion in an E. coli slyA mutant was reduced to 60\% of the wild-type level confirming a positive role for SlyA. DNase I footprint analysis revealed the presence of two separate SlyA binding sites, one located upstream, the other downstream of the hlyE transcriptional start site. These sites overlap AT-rich H-NS binding sites. Footprint and gel shift data showed that whereas H-NS prevented binding of RNA polymerase (RNAP) at the hlyE promoter (PhlyE), SlyA allowed binding of RNAP, but inhibited binding of H-NS. Accordingly, in vitro transcription analyses showed that addition of SlyA protein relieved H-NS-mediated repression of hlyE. Based on these observations a model for SlyA/H-NS regulation of hlyE expression is proposed in which the relative concentrations of SlyA and H-NS govern the nature of the nucleoprotein complexes formed at PhlyE. When H-NS is dominant RNAP binding is inhibited and hlyE expression is silenced; when SlyA is dominant H-NS binding is inhibited allowing RNAP access to the promoter facilitating hlyE transcription.}, address = {Department of Molecular Biology and Biotechnology, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK.}, author = {Lithgow, J. K. and Haider, F. and Roberts, I. S. and Green, J. }, citeulike-article-id = {2759162}, doi = {10.1111/j.1365-2958.2007.05950.x}, issn = {0950-382X}, journal = {Molecular microbiology}, keywords = {regulatorynetworks}, month = {November}, number = {3}, pages = {685--698}, posted-at = {2008-05-05 21:38:52}, priority = {2}, title = {Alternate SlyA and H-NS nucleoprotein complexes control hlyE expression in Escherichia coli K-12.}, url = {http://dx.doi.org/10.1111/j.1365-2958.2007.05950.x}, volume = {66}, year = {2007} }

TY - JOUR ID - SlyAHNScontrolhlyE L3 - citeulike-article-id:2759162 TI - Alternate SlyA and H-NS nucleoprotein complexes control hlyE expression in Escherichia coli K-12. JF - Molecular microbiology VL - 66 IS - 3 SP - 685 EP - 698 AD - Department of Molecular Biology and Biotechnology, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK. SN - 0950-382X N2 - Haemolysin E is a cytolytic pore-forming toxin found in several Escherichia coli and Salmonella enterica strains. Expression of hlyE is repressed by the global regulator H-NS (histone-like nucleoid structuring protein), but can be activated by the regulator SlyA. Expression of a chromosomal hlyE-lacZ fusion in an E. coli slyA mutant was reduced to 60% of the wild-type level confirming a positive role for SlyA. DNase I footprint analysis revealed the presence of two separate SlyA binding sites, one located upstream, the other downstream of the hlyE transcriptional start site. These sites overlap AT-rich H-NS binding sites. Footprint and gel shift data showed that whereas H-NS prevented binding of RNA polymerase (RNAP) at the hlyE promoter (PhlyE), SlyA allowed binding of RNAP, but inhibited binding of H-NS. Accordingly, in vitro transcription analyses showed that addition of SlyA protein relieved H-NS-mediated repression of hlyE. Based on these observations a model for SlyA/H-NS regulation of hlyE expression is proposed in which the relative concentrations of SlyA and H-NS govern the nature of the nucleoprotein complexes formed at PhlyE. When H-NS is dominant RNAP binding is inhibited and hlyE expression is silenced; when SlyA is dominant H-NS binding is inhibited allowing RNAP access to the promoter facilitating hlyE transcription. KW - regulatorynetworks AU - Lithgow, JK AU - Haider, F AU - Roberts, IS AU - Green, J PY - 2007/11// UR - http://dx.doi.org/10.1111/j.1365-2958.2007.05950.x ER -