N-succinylglutamate 5-semialdehyde dehydrogenase or succinylglutamic semialdehyde dehydrogenase (SGSD, E. coli AstD, EC=1.2.1.71) involved in L-arginine degradation via the arginine succinyltransferase (AST) pathway and catalyzes the NAD+-dependent reduction of succinylglutamate semialdehyde into succinylglutamate.