Linked Life Data

1779767

Source:http://linkedlifedata.com/resource/pubmed/id/1779767

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
11
pubmed:dateCreated
1992-3-10
pubmed:abstractText
The products of a minimum of 15 genes are required for the synthesis of an active formate-hydrogenlyase (FHL) system in Escherichia coli. All are co-ordinately regulated in response to variations in the oxygen and nitrate concentration and the pH of the culture medium. Formate is obligately required for transcriptional activation of these genes. Analysis of the transcription of one of these genes, hycB linked to the lacZ reporter gene, revealed that oxygen and nitrate repression of transcription could be relieved completely, or partially in the case of nitrate, either by the addition of formate to the medium or by increasing the copy number of the gene encoding the transcriptional activator (fhlA) of this regulon. These studies uncovered a further level of regulation in which the transcription of hycB was reduced in cells grown on glucose. This effect was most clearly seen in aerobically grown cells when formate was added externally. Addition of cAMP overcame this glucose repression, which could be shown to be mediated by the cAMP receptor protein. These results would be consistent with the transport of formate being regulated by catabolite repression. Moreover, the repression of transcription through high pH also could be partially overcome by addition of increasing concentrations of formate to the medium, again being consistent with regulation at the level of formate import and export. Taken together, all these observations indicate that it is the intracellular level of formate that determines the transcription of the genes of the formate regulon by FhlA. This represents a novel positive feedback mechanism in which the activator of a regulon induces its own synthesis in response to increases in the concentration of the catabolic substrate, and this in turn is governed by the relative affinities of FhlA and the three formate dehydrogenase isoenzymes for formate.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0950-382X
pubmed:author
pubmed:issnType
Print
pubmed:volume
5
pubmed:geneSymbol
crp, fdfH, fdhF, fhlA, hyc, hycA, hycB, hypA, hypE
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2807-14
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Mechanism of regulation of the formate-hydrogenlyase pathway by oxygen, nitrate, and pH: definition of the formate regulon.
pubmed:affiliation
Lehrstuhl für Mikrobiologie der Universität, München, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't