Involved in the synthesis of meso-diaminopimelate (m-DAP or DL-DAP), required for both lysine and peptidoglycan biosynthesis. Catalyzes the direct conversion of tetrahydrodipicolinate to LL-diaminopimelate, a reaction that requires three enzymes in E.coli. (2S,6S)-2,6-diaminoheptanedioate + 2-oxoglutarate = (S)-2,3,4,5-tetrahydrodipicolinate + H(+) + H2O + L-glutamate Optimum pH is 8.5. About 40% and 50% of the maximum activity are observed at pH 7.0 and 10.0, respectively. Optimum temperature is 70 degrees Celsius. No activity is detected at temperatures below 45 degrees Celsius. At 85 degrees Celsius, the activity is 85% of the maximum activity. Amino-acid biosynthesis; L-lysine biosynthesis via DAP pathway; LL-2,6-diaminopimelate from (S)-tetrahydrodipicolinate (aminotransferase route): step 1/1. Homodimer. Belongs to the class-I pyridoxal-phosphate-dependent aminotransferase family.