Main aspartate aminotransferase that couples nitrogen assimilation to aspartate synthesis. Has a weak, but significant, side activity toward kynurenine (Kyn). Oxaloacetate and 2-oxoglutarate, but not pyruvate, serve as amino acceptors, while Asp, Glu and Kyn serve as the best amino donors. Essential for axenic growth and survival of M.tuberculosis in macrophages and in mice. 2-oxoglutarate + L-aspartate = L-glutamate + oxaloacetate kcat is 136 sec(-1) with aspartate as substrate. kcat is 198 sec(-1) with kynurenine as substrate. Deletion of the gene leads to virulence attenuation in macrophages and mice. Belongs to the class-I pyridoxal-phosphate-dependent aminotransferase family.