GabR, a member of a novel protein family, regulates the utilization of gamma-aminobutyrate in Bacillus subtilis.
The Bacillus subtilis ycnG (gabT) and ycnH (gabD) genes were shown to encode gamma-aminobutyrate (GABA) aminotransferase and succinic semi-aldehyde dehydrogenase, respectively, and to form a GABA-inducible operon. Null mutations in gabT, gabD or the divergently transcribed ycnF (gabR) gene blocked the utilization of GABA as sole nitrogen source. GabR proved to be a transcriptional activator of the gabTD operon and a negative autoregulator. The target of GabR action was localized to an 87 bp region that includes both gabR and gabT promoters. GabR is a member of a novel but widespread family of chimeric bacterial proteins that have apparent DNA-binding and aminotransferase domains. Mutations in conserved residues of the putative aminotransferase domain abolished GabR function as a transcriptional activator, but did not affect its activity as a negative autoregulator.
Belitsky
Boris R
BR
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111, USA. bbelit02@tufts.edu
Sonenshein
Abraham L
AL
D000612:4-Aminobutyrate Transaminase / Q000235:genetics / Q000502:physiology*; D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000502:physiology*; D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial / Q000235:genetics; D003001:Cloning, Molecular; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D005810:Multigene Family; D009584:Nitrogen / Q000378:metabolism; D009876:Operon / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D050644:Succinate-Semialdehyde Dehydrogenase; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D001426:Bacterial Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D005680:gamma-Aminobutyric Acid; D000445:Aldehyde Oxidoreductases; D050644:Succinate-Semialdehyde Dehydrogenase; D000612:4-Aminobutyrate Transaminase; D009584:Nitrogen