Catalyzes the transamination of N(2)-succinylornithine and alpha-ketoglutarate into N(2)-succinylglutamate semialdehyde and glutamate. Can also act as an acetylornithine aminotransferase. 2-oxoglutarate + N(2)-succinyl-L-ornithine = L-glutamate + N-succinyl-L-glutamate 5-semialdehyde Amino-acid degradation; L-arginine degradation via AST pathway; L-glutamate and succinate from L-arginine: step 3/5. By nitrogen and carbon starvation, and arginine, via the ArgR and Crp transcriptional regulators. Belongs to the class-III pyridoxal-phosphate-dependent aminotransferase family. AstC subfamily.