Linked Life Data

7921262

Source:http://linkedlifedata.com/resource/pubmed/id/7921262

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
1994-11-21
pubmed:abstractText
Repression of tryptophanase (tryptophan indole-lyase) by glucose and its non-metabolizable analogue methyl alpha-glucoside has been studied employing a series of isogenic strains of Escherichia coli lacking cyclic AMP phosphodiesterase and altered for two of the proteins of the phosphoenolpyruvate:sugar phosphotransferase system (PTS), Enzyme I and Enzyme IIAGlc. Basal activity of tryptophanase was depressed mildly by inclusion of glucose in the growth medium, but inducible tryptophanase synthesis was subject to strong glucose repression in the parental strain, which exhibited normal PTS enzyme activities. Methyl alpha-glucoside was without effect in this strain. Loss of Enzyme I decreased sensitivity to repression by glucose but enhanced sensitivity to repression by methyl alpha-glucoside. Loss of Enzyme IIAGlc activity largely abolished repression by methyl alpha-glucoside but had a less severe effect on glucose repression. The repressive effects of both sugars were fully reversed by inclusion of cyclic AMP in the growth medium. Tryptophan uptake under the same conditions was inhibited weakly by glucose and more strongly by methyl alpha-glucoside in the parental strain. Inhibition by both sugars was alleviated by partial loss of Enzyme I. Inhibition by methyl alpha-glucoside appeared to be largely due to energy competition and was not responsible for repression of tryptophanase synthesis. Measurement of net production of cyclic AMP as well as intracellular concentrations of cyclic AMP revealed a good correlation with intensity of repression. The results suggest that while basal tryptophanase synthesis is relatively insensitive to catabolite repression, inducible synthesis is subject to strong repression by two distinct mechanisms, one dependent on enzyme IIAGlc of the PTS and the other independent of this protein. Both mechanisms are attributable to depressed rates of cyclic AMP synthesis. No evidence for a cyclic-AMP-independent mechanism of catabolite repression was obtained.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/3',5'-Cyclic-AMP Phosphodiesterases, http://linkedlifedata.com/resource/pubmed/chemical/Bacterial Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Cyclic AMP, http://linkedlifedata.com/resource/pubmed/chemical/Glucose, http://linkedlifedata.com/resource/pubmed/chemical/Methylglucosides, http://linkedlifedata.com/resource/pubmed/chemical/Phosphoenolpyruvate Sugar..., http://linkedlifedata.com/resource/pubmed/chemical/Phosphotransferases (Nitrogenous..., http://linkedlifedata.com/resource/pubmed/chemical/Tryptophan, http://linkedlifedata.com/resource/pubmed/chemical/Tryptophanase, http://linkedlifedata.com/resource/pubmed/chemical/methylglucoside, http://linkedlifedata.com/resource/pubmed/chemical/phosphoenolpyruvate-glucose..., http://linkedlifedata.com/resource/pubmed/chemical/phosphoenolpyruvate-protein...
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
1350-0872
pubmed:author
pubmed:issnType
Print
pubmed:volume
140 ( Pt 8)
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2125-34
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Mechanism of catabolite repression of tryptophanase synthesis in Escherichia coli.
pubmed:affiliation
Department of Biology, University of California at San Diego, La Jolla 92093-0116.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.