Catalyzes the reversible conversion of aspartate and 2-oxoglutarate to glutamate and oxaloacetate (PubMed:8096210, PubMed:24302739). Can also transaminate prephenate in the presence of glutamate (PubMed:24302739). Required for symbiotic nitrogen fixation (PubMed:2019560). 2-oxoglutarate + L-aspartate = L-glutamate + oxaloacetate 2-oxoglutarate + L-arogenate = L-glutamate + prephenate kcat is 205 sec(-1) with oxaloacetate as substrate. kcat is 43 sec(-1) with prephenate as substrate. Homodimer. Mutant is unable to grow on aspartate but can grow on other carbon and nitrogen sources. Mutant is unable to fix nitrogen within nodules formed on alfalfa. Belongs to the class-I pyridoxal-phosphate-dependent aminotransferase family.