Document Detail

Metalloregulation in vitro of the aerobactin promoter of Escherichia coli by the Fur (ferric uptake regulation) protein.
MedLine Citation:
PMID:  9427409     Owner:  NLM     Status:  MEDLINE    
The mechanism of transcriptional repression of the aerobactin operon of Escherichia coli by the Fe2+-responsive Fur (ferric uptake regulation) protein has been investigated. In the presence of a divalent metal, such as Mn2+, the Fur protein sequentially occupies two defined sites at the aerobactin promoter region, followed by a looser occupation of upstream DNA sequences. However, binding to the primary target site suffices for the entire repression effect. Comparison of transcription patterns generated with run-off experiments in the presence and absence of heparin showed that access of the RNA polymerase to the principal -35/-10 hexamers of the promoter region was fully prevented by Fur-Mn2+ bound to its primary site. Similarly, promoter-bound RNA polymerase could not be competed out from the DNA even in the presence of a large Fur-Mn2+ excess, although the repressor could immediately bind its target sequence at the region as soon as RNA polymerase moved away from the promoter during transcription. The high affinities of either protein for the promoter produce, in practice, a first-come, first-served effect that helps the system to respond instantly to changes in the iron status of the cells.
L Escolar; V de Lorenzo; J Pérez-Martín
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Molecular microbiology     Volume:  26     ISSN:  0950-382X     ISO Abbreviation:  Mol. Microbiol.     Publication Date:  1997 Nov 
Date Detail:
Created Date:  1998-02-19     Completed Date:  1998-02-19     Revised Date:  2010-10-19    
Medline Journal Info:
Nlm Unique ID:  8712028     Medline TA:  Mol Microbiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  799-808     Citation Subset:  IM    
Centro Nacional de Biotecnología, Campus de Cantoblanco, Madrid, Spain.
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MeSH Terms
Bacterial Proteins / metabolism*
DNA-Binding Proteins / metabolism*
DNA-Directed RNA Polymerases / metabolism*
Deoxyribonuclease I / metabolism
Escherichia coli / genetics*,  metabolism
Gene Expression Regulation, Bacterial
Hydroxamic Acids*
Manganese / metabolism
Promoter Regions, Genetic*
Repressor Proteins / metabolism*
Transcription, Genetic*
Reg. No./Substance:
0/Bacterial Proteins; 0/DNA-Binding Proteins; 0/Hydroxamic Acids; 0/Repressor Proteins; 0/ferric uptake regulating proteins, bacterial; 26198-65-2/aerobactin; 7439-96-5/Manganese; EC RNA Polymerases; EC I

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