A mixed double negative feedback loop between the sRNA MicF and the global regulator Lrp

• Roughly 10% of all genes in Escherichia coli are controlled by the global transcription factor Lrp, which responds to nutrient availability. Bioinformatically, we identified lrp as one of several putative targets for the sRNA MicF, which is transcriptionally downregulated by Lrp. Deleting micF results in higher Lrp levels, while overexpression of MicF inhibits Lrp synthesis. This effect is by antisense; mutations in the predicted interaction region relieve MicF-dependent repression of Lrp synthesis, and regulation is restored by compensatory mutations. In vitro, MicF sterically interferes with initiation complex formation and inhibits lrp mRNA translation. In vivo, MicF indirectly activates genes in the Lrp regulon by repressing Lrp, and causes severely impaired growth in minimal medium, a phenotype characteristic of lrp deletion strains. The double negative feedback between MicF and Lrp may promote a switch for adequate Lrp-dependent adaptation to nutrient availability. Lrp adds to the growing list of transcription factors that are targeted by sRNAs, thus indicating that perhaps the majority of all bacterial genes may be directly or indirectly controlled by sRNAs.

Ämnesord

NATURVETENSKAP  -- Biologi -- Mikrobiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Microbiology (hsv//eng)

Nyckelord

MicF

Lrp

sRNA

transcription factor

feedback regulation

Biology with specialization in Microbiology

Biologi med inriktning mot mikrobiologi

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)