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 (PubMed:17093042, PubMed:21722650). Is also able to use meso-diaminopimelate, cystathionine, lysine or ornithine as substrates (PubMed:17093042). (2S,6S)-2,6-diaminoheptanedioate + 2-oxoglutarate = (S)-2,3,4,5-tetrahydrodipicolinate + H(+) + H2O + L-glutamate Amino-acid biosynthesis; L-lysine biosynthesis via DAP pathway; LL-2,6-diaminopimelate from (S)-tetrahydrodipicolinate (aminotransferase route): step 1/1. Homodimer. Expressed as early as 8 hours after infection. Belongs to the class-I pyridoxal-phosphate-dependent aminotransferase family. LL-diaminopimelate aminotransferase subfamily.