Global InformationGab operon information
The gab operon is responsible for the conversion of γ-aminobutyrate (GABA) to succinate. The gab operon comprises three structural genes – gabD, gabT and gabP – that encode for a succinate semialdehyde dehydrogenase, GABA transaminase and a GABA permease respectively. There is a regulatory gene csiR, downstream of the operon, that codes for a putative transcriptional repressor[1] and is activated when nitrogen is limiting.
The gab operon has been characterized in Escherichia coli and significant homologies for the enzymes have been found in organisms such as Saccharomyces cerevisiae, rats and humans.[2]
Limited nitrogen conditions activate the gab genes. The enzymes produced by these genes convert GABA to succinate, which then enters the TCA cycle, to be used as a source of energy. The gab operon is also known to contribute to polyamine homeostasis during nitrogen-limited growth and to maintain high internal glutamate concentrations under stress conditions.[3]
- ^ Schneider, Barbara L.; Ruback, Stephen; Kiupakis, Alexandros K.; Kasbarian, Hillary; Pybus, Christine; Reitzer, Larry (2002). "The Escherichia coli gabDTPC Operon: Specific γ-Aminobutyrate Catabolism and Nonspecific Induction". Journal of Bacteriology. 184 (24): 6976–86. doi:10.1128/JB.184.24.6976-6986.2002. PMC 135471. PMID 12446648.
- ^ Bartsch, Klaus; Von Johnn-Marteville, Astrid; Schulz, Arno (1990). "Molecular Analysis of Two Genes of the Escherichia coli gab Cluster: Nucleotide Sequence of the Glutamate:Succinic Semialdehyde Transaminase Gene (gabT) and Characterization of the Succinic Semialdehyde Dehydrogenase Gene (gabD)". Journal of Bacteriology. 172 (12): 7035–42. doi:10.1128/jb.172.12.7035-7042.1990. PMC 210825. PMID 2254272.
- ^ Metzner, Martin; Germer, Jens; Hengge, Regine (2003). "Multiple stress signal integration in the regulation of the complex σS-dependent csiD-ygaF-gabDTP operon in Escherichia coli". Molecular Microbiology. 51 (3): 799–811. doi:10.1046/j.1365-2958.2003.03867.x. PMID 14731280.