Catalyzes the reversible conversion of aspartate and 2-oxoglutarate to glutamate and oxaloacetate. 2-oxoglutarate + L-aspartate = L-glutamate + oxaloacetate Optimum pH is 8.0-8.5. Homodimer. Insertion mutant is prototroph and is able to carry out symbiotic nitrogen fixation. Belongs to the class-I pyridoxal-phosphate-dependent aminotransferase family.