| Primary Identifier | IPR012375 | Type | Family |
| Short Name | Glu_synth_lsu_1 |
| description | The large (alpha, GltB) subunit of bacterial glutamate synthase (GOGAT, GltS) consists of three domains. This entry represents a stand-alone version of the N-terminal amidotransferase domain that is found in archaeal GOGAT, where the large subunit is represented by three separate proteins corresponding to the three domains of the "standard"bacterial enzyme []. Similar organisation of GOGAT with stand-alone domains has been found in some bacteria (e.g., Sinorhizobium meliloti and Thermotoga maritima), but its function is not clear in those organisms where the "standard"(integrated) bacterial form is also present (e.g., Sinorhizobium meliloti).The amidotransferase domain of the bacterial GOGAT is characterised by a four layer alpha/beta/beta/alpha architecture []and contains the typical catalytic centre. The N-terminal Cys-1 catalyses the hydrolysis of L-glutamine generating ammonia and the first molecule of L-glutamate [].Originally, only the ORF encoding the central domain of GOGAT was recognised and annotated as GltB in archaea, and the rest of the large subunit was thought to be missing, which may lead to some misannotations []. This led to speculation that the archaeal form of the GOGAT large subunit was the ancestral minimal form of the enzyme. Later analysis showed, however, that in all archaea where the large subunit has been found, its entire sequence is represented by three separate ORFs [].Glutamate synthase is a complex iron-sulphur flavoprotein that catalyses the reductive synthesis of L-glutamate from 2-oxoglutarate and L-glutamine via intramolecular channeling of ammonia, a reaction in the bacterial, yeast and plant pathways for ammonia assimilation []. GOGAT is a multifunctional enzyme that functions through three distinct active centres carrying out multiple reaction steps: L-glutamine hydrolysis, conversion of 2-oxoglutarate into L-glutamate, and electron uptake from an electron donor []. |
