Linked Life Data

10027963

Source:http://linkedlifedata.com/resource/pubmed/id/10027963

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1999-4-29
pubmed:abstractText
Efficient repression of the two promoters P1 and P2 of the gal operon requires the formation of a DNA loop encompassing the promoters. In vitro, DNA looping-mediated repression involves binding of the Gal repressor (GalR) to two gal operators (OE and OI) and binding of the histone-like protein HU to a specific locus (hbs) about the midpoint between OE and OI, and supercoiled DNA. Without DNA looping, GalR binding to OE partially represses P1 and stimulates P2. We investigated the requirement for DNA supercoiling and HU in repression of the gal promoters in vivo in strains containing a fusion of a reporter gene, gusA or lacZ, to each promoter individually. While the P1 promoter was found to be repressible in the absence of DNA supercoiling and HU, the repression of P2 was entirely dependent upon DNA supercoiling in vivo. The P2 promoter was fully derepressed when supercoiling was inhibited by the addition of coumermycin in cells. P2, but not P1, was also totally derepressed by the absence of HU or the OI operator. From these results, we propose that the repression of the gal promoters in vivo is mediated by the formation of a higher order DNA-multiprotein complex containing GalR, HU and supercoiled DNA. In the absence of this complex, P1 but not P2 is still repressed by GalR binding to OE. The specific nucleoprotein complexes involving histone-like proteins, which repress promoter activity while remaining sensitive to inducing signals, as discussed, may occur more generally in bacterial nucleoids.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/Aminocoumarins, http://linkedlifedata.com/resource/pubmed/chemical/Bacterial Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Coumarins, http://linkedlifedata.com/resource/pubmed/chemical/DNA, Superhelical, http://linkedlifedata.com/resource/pubmed/chemical/DNA-Binding Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Enzyme Inhibitors, http://linkedlifedata.com/resource/pubmed/chemical/Escherichia coli Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Galactose repressor proteins, http://linkedlifedata.com/resource/pubmed/chemical/Nucleoproteins, http://linkedlifedata.com/resource/pubmed/chemical/Repressor Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Topoisomerase II Inhibitors, http://linkedlifedata.com/resource/pubmed/chemical/coumermycin, http://linkedlifedata.com/resource/pubmed/chemical/histone-like protein HU, bacteria
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0950-382X
pubmed:author
pubmed:issnType
Print
pubmed:volume
31
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
451-61
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Role of HU and DNA supercoiling in transcription repression: specialized nucleoprotein repression complex at gal promoters in Escherichia coli.
pubmed:affiliation
Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4255, USA.
pubmed:publicationType
Journal Article