Open AccessNifA-dependent in vivo protection demonstrates that the upstream activator sequence of nif promoters is a protein binding site.
Author(s) -
Enrique Morett,
Martin Buck
Publication year - 1988
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.85.24.9401
Subject(s) - promoter , activator (genetics) , methylation , biology , binding site , primer extension , guanine , dna , gene , consensus sequence , transcription factor , microbiology and biotechnology , dna binding protein , upstream activating sequence , transcription (linguistics) , dna methylation , genetics , peptide sequence , gene expression , nucleotide , linguistics , philosophy
Primer-extension analysis of the Klebsiella pneumoniae nifH promoter was used to determine changes in the accessibility of the promoter DNA to methylation after exposure of growing cells to dimethyl sulfate. Four guanine residues present in the nifH upstream activator sequence (UAS), the proposed NifA binding site, were protected from methylation and two guanine residues were hypermethylated when the transcriptional activator protein NifA was present in the cells. The interaction detected at the nifH UAS was independent of the alternative sigma factor NtrA required for transcription of the nifH and other nif promoters. Mutations within the nifH UAS that diminish NifA-dependent transcriptional activation reduced the interaction at the UAS. It seems likely that the pattern of methylation protection observed in the nifH UAS is the result of NifA binding.