Linked Life Data

1943705

Source:http://linkedlifedata.com/resource/pubmed/id/1943705

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
1991-12-13
pubmed:abstractText
AmpR, the transcriptional regulator for the Citrobacter freundii ampC beta-lactamase gene, was purified. The purified AmpR had DNA-binding activity, the same molecular mass (32 kDa) on sodium dodecyl sulphate/polyacrylamide gel electrophoresis as previously described, and N-terminal sequencing of the first 15 amino acids was in agreement with that predicted from the nucleotide sequence. Two mutants were isolated that abolish DNA-binding and beta-lactamase induction and which map in the amino- and carboxyl-terminal ends of AmpR, respectively. The mutation in the amino terminus (S35F) was located in a helix-turn-helix region showing high homology to other members of the LysR regulator family. Therefore this mutation may directly abolish the contact between AmpR and its operator sequence. It is suggested that the C-terminal mutation (Y264N) affects subunit interactions in AmpR. One constitutive mutant was isolated which mapped in the centre of the ampR gene. This G102E mutant leads to constitutive beta-lactamase expression in the absence of both beta-lactam inducer and ampG, a gene essential for induction in wild-type enterobacteria. Another mutant protein, D135Y, showed wild-type properties in an ampG+ and an ampG::kan background, but could, unlike wild-type AmpR, activate the ampC gene in an ampG1 mutant background. It is thought that ampG1 is a missense mutant. These two types of ampR mutants suggest that activation of ampC transcription is dependent on the conversion of AmpR into a transcriptional activator and that this activation may normally involve interactions with AmpG.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0950-382X
pubmed:author
pubmed:issnType
Print
pubmed:volume
5
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1715-25
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Purification and mutant analysis of Citrobacter freundii AmpR, the regulator for chromosomal AmpC beta-lactamase.
pubmed:affiliation
Department of Molecular Microbiology, Washington University, Medical School, St Louis, Missouri 63110.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't