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. 1987 Dec 10;15(23):9945–9956. doi: 10.1093/nar/15.23.9945

Mutational analysis of upstream sequences required for transcriptional activation of the Klebsiella pneumoniae nifH promoter.

M Buck 1, W Cannon 1, J Woodcock 1
PMCID: PMC306542  PMID: 3320958

Abstract

Upstream sequences of the Klebsiella pneumoniae nifH promoter were mutagenised and activation of the mutated promoters by the nif-specific transcriptional activator protein NifA examined in vivo. Of the sixteen mutations analysed, only those within the nifH upstream activator sequence (UAS), characterised by a TGT-N10-ACA motif, influenced nifH promoter activity. Mutations altering the two-fold rotational symmetry of the UAS or the spacing between the TGT and ACA motifs reduced promoter activity, consistent with the UAS functioning as a NifA binding site. The bases flanking the TGT-ACA motif of the UAS also appear to influence activation by NifA. Substituting the nifH UAS with a binding site for the transcriptional activator NtrC resulted in improved NtrC-dependent activation of the nifH promoter demonstrating that the activator specificity of the nifH promoter is dependent upon the presence of the appropriate upstream sequences to which the activator binds.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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