Molecular mechanisms of regulation by a β‐alanine‐responsive Lrp‐type transcription factor from Acidianus hospitalis

Molecular mechanisms of regulation by a beta-alanine-responsive Lrp-type transcription factor fromAcidianus hospitalis. AbstractThe leucine-responsive regulatory protein (Lrp) family of transcriptional regulators is widespread among prokaryotes and especially well-represented in archaea. It harbors members with diverse functional mechanisms and physiological roles, often linked to the regulation of amino acid metabolism. BarR is an Lrp-type regulator that is conserved in thermoacidophilic Thermoprotei belonging to the order Sulfolobales and is responsive to the non-proteinogenic amino acid β-alanine. In this work, we unravel molecular mechanisms of theAcidianus hospitalis BarR homolog, Ah-BarR. Using a heterologous reporter gene system inEscherichia coli, we demonstrate that Ah-BarR is a dual-function transcription regulator that is capable of repressing transcription of its own gene and activating transcription of an aminotransferase gene, which is divergently transcribed from a common intergenic region. Atomic force microscopy (AFM) visualization reveals a conformation in which the intergenic region appears wrapped around an octameric Ah-BarR protein. β-alanine causes small conformational changes without affecting the oligomeric state of the protein, resulting in a relief of regulation while the regulator remains bound to the DNA. This regulatory and ligand response is different from the orthologous regulators inSulfolobus acidocaldarius andSulfurisphaera tokodaii, which ...
Source: MicrobiologyOpen - Category: Microbiology Authors: Tags: ORIGINAL ARTICLE Source Type: research