Required for lysine biosynthesis. Catalyzes the direct conversion of tetrahydrodipicolinate to LL-diaminopimelate, a reaction that requires three enzymes in E.coli. Not active with meso-diaminopimelate, lysine or ornithine as substrates. (2S,6S)-2,6-diaminoheptanedioate + 2-oxoglutarate = (S)-2,3,4,5-tetrahydrodipicolinate + H(+) + H2O + L-glutamate Optimum pH is 7.9 in Tris buffer and 7.6 in HEPES buffer. Optimum temperature is 36 degrees Celsius. Amino-acid biosynthesis; L-lysine biosynthesis via DAP pathway; LL-2,6-diaminopimelate from (S)-tetrahydrodipicolinate (aminotransferase route): step 1/1. Homodimer. Highly expressed in seedlings, roots, stems, flowers and leaves. Lower expression in siliques. Down-regulated during senescence. Not induced by pathogen infection, but down-regulated by dark treatment. Embryonic lethality. The expected covalent binding of pyridoxal phosphate by Lys-305 has not been observed in the 3D-structure. Belongs to the class-I pyridoxal-phosphate-dependent aminotransferase family. LL-diaminopimelate aminotransferase subfamily.