Devoted to catabolic function of glutamate (and other amino acids of the glutamate family) utilization as sole nitrogen source. It is not involved in anabolic function of glutamate biosynthesis since B.subtilis possesses only one route of glutamate biosynthesis from ammonia, catalyzed by glutamate synthase. Wild-type cells are unable to utilize glutamate or glutamine as a sole carbon source; thus RocG does not function physiologically to synthesize glutamate, but it is involved in the utilization of arginine, and proline as carbon or nitrogen source (PubMed:9829940). The catabolic RocG is essential for controlling gltAB expression via an inhibitory interactions with the transcriptional regulator GltC in response to the availability of sugars (PubMed:17183217, PubMed:15150224). H2O + L-glutamate + NAD(+) = 2-oxoglutarate + H(+) + NADH + NH4(+) Optimum pH is 7.7 and 7.3 for L-glutamate deamination and 2-oxoglutarate amination, respectively. Half-maximal activity for deamination is observed at pH 6.9 and 7.8 and that for amination is at pH 6.9 and 7.8. Low thermostability at 41 degrees Celsius due to the dissociation of the hexamer. Homohexamer (PubMed:16244435, PubMed:20630473). Interacts with transcriptional regulator GltC (PubMed:17608797). Enzyme activity is low in early exponential phase and reached higher levels in the middle and late stages of exponential growth (at protein level). Repressed by glucose; induced by arginine, ornithine, or to a lesser extent proline (in the absence of glucose). Not induced by glutamate or glutamine (PubMed:9829940). Expression depends on the alternative sigma-L factor and the transcription factor RocR (PubMed:10468601). Subject to direct CcpA-dependent glucose repression (PubMed:15150224). Cells lacking this gene lose the ability to utilize proline, ornithine, or arginine as sole carbon source and grow more slowly when proline or ornithine is utilized as sole nitrogen source in the presence of glucose. A double rocG-gudB disruption has the same phenotype as a single rocG disruption. Belongs to the Glu/Leu/Phe/Val dehydrogenases family.