BarR, an Lrp-type transcription factor in Sulfolobus acidocaldarius, regulates an aminotransferase gene in a beta- alanine responsive manner
2014 (English)In: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 92, no 3, 625-639 p.Article in journal (Refereed) Published
In archaea, nothing is known about the -alanine degradation pathway or its regulation. In this work, we identify and characterize BarR, a novel Lrp-like transcription factor and the first one that has a non-proteinogenic amino acid ligand. BarR is conserved in Sulfolobus acidocaldarius and Sulfolobus tokodaii and is located in a divergent operon with a gene predicted to encode -alanine aminotransferase. Deletion of barR resulted in a reduced exponential growth rate in the presence of -alanine. Furthermore, qRT-PCR and promoter activity assays demonstrated that BarR activates the expression of the adjacent aminotransferase gene, but only upon -alanine supplementation. In contrast, auto-activation proved to be -alanine independent. Heterologously produced BarR is an octamer in solution and forms a single complex by interacting with multiple sites in the 170bp long intergenic region separating the divergently transcribed genes. In vitro, DNA binding is specifically responsive to -alanine and site-mutant analyses indicated that -alanine directly interacts with the ligand-binding pocket. Altogether, this work contributes to the growing body of evidence that in archaea, Lrp-like transcription factors have physiological roles that go beyond the regulation of -amino acid metabolism.
Place, publisher, year, edition, pages
2014. Vol. 92, no 3, 625-639 p.
Biochemistry and Molecular Biology Microbiology
IdentifiersURN: urn:nbn:se:su:diva-104133DOI: 10.1111/mmi.12583ISI: 000334857400014OAI: oai:DiVA.org:su-104133DiVA: diva2:721616