Feil Family Brain & Mind Research Institute

You are here

PLP and GABA trigger GabR-mediated transcription regulation in Bacillus subtilis via external aldimine formation.

TitlePLP and GABA trigger GabR-mediated transcription regulation in Bacillus subtilis via external aldimine formation.
Publication TypeJournal Article
Year of Publication2017
AuthorsWu R, Sanishvili R, Belitsky BR, Juncosa JI, Le HV, Lehrer HJS, Farley M, Silverman RB, Petsko GA, Ringe D, Liu D
JournalProc Natl Acad Sci U S A
Volume114
Issue15
Pagination3891-3896
Date Published2017 Apr 11
ISSN1091-6490
Abstract

The Bacillus subtilis protein regulator of the gabTD operon and its own gene (GabR) is a transcriptional activator that regulates transcription of γ-aminobutyric acid aminotransferase (GABA-AT; GabT) upon interactions with pyridoxal-5'-phosphate (PLP) and GABA, and thereby promotes the biosynthesis of glutamate from GABA. We show here that the external aldimine formed between PLP and GABA is apparently responsible for triggering the GabR-mediated transcription activation. Details of the "active site" in the structure of the GabR effector-binding/oligomerization (Eb/O) domain suggest that binding a monocarboxylic γ-amino acid such as GABA should be preferred over dicarboxylic acid ligands. A reactive GABA analog, (S)-4-amino-5-fluoropentanoic acid (AFPA), was used as a molecular probe to examine the reactivity of PLP in both GabR and a homologous aspartate aminotransferase (Asp-AT) from Escherichia coli as a control. A comparison between the structures of the Eb/O-PLP-AFPA complex and Asp-AT-PLP-AFPA complex revealed that GabR is incapable of facilitating further steps of the transamination reaction after the formation of the external aldimine. Results of in vitro and in vivo assays using full-length GabR support the conclusion that AFPA is an agonistic ligand capable of triggering GabR-mediated transcription activation via formation of an external aldimine with PLP.

DOI10.1073/pnas.1703019114
Alternate JournalProc. Natl. Acad. Sci. U.S.A.
PubMed ID28348215
PubMed Central IDPMC5393194
Grant ListR01 DA030604 / DA / NIDA NIH HHS / United States
R15 GM113229 / GM / NIGMS NIH HHS / United States