BarR, an Lrp-type transcription factor in Sulfolobus acidocaldarius, regulates an aminotransferase gene in a β-alanine responsive manner

Mol Microbiol. 2014 May;92(3):625-39. doi: 10.1111/mmi.12583. Epub 2014 Apr 8.

Abstract

In archaea, nothing is known about the β-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 β-alanine aminotransferase. Deletion of barR resulted in a reduced exponential growth rate in the presence of β-alanine. Furthermore, qRT-PCR and promoter activity assays demonstrated that BarR activates the expression of the adjacent aminotransferase gene, but only upon β-alanine supplementation. In contrast, auto-activation proved to be β-alanine independent. Heterologously produced BarR is an octamer in solution and forms a single complex by interacting with multiple sites in the 170 bp long intergenic region separating the divergently transcribed genes. In vitro, DNA binding is specifically responsive to β-alanine and site-mutant analyses indicated that β-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 α-amino acid metabolism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA Mutational Analysis
  • DNA, Archaeal / metabolism
  • Gene Deletion
  • Gene Expression Profiling
  • Gene Expression Regulation*
  • Protein Binding
  • Protein Multimerization
  • Real-Time Polymerase Chain Reaction
  • Sulfolobus acidocaldarius / genetics*
  • Sulfolobus acidocaldarius / metabolism*
  • Transaminases / biosynthesis*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • beta-Alanine / metabolism*

Substances

  • DNA, Archaeal
  • Transcription Factors
  • beta-Alanine
  • Transaminases

Associated data

  • PDB/2E7X
  • PDB/2EZW