EC 1.3.1.26      
Transferred entry: dihydrodipicolinate reductase. Now EC 1.17.1.8, 4-hydroxy-tetrahydrodipicolinate reductase.
[EC 1.3.1.26 created 1976, modified 2011, deleted 2013]
 
 
EC 1.17.1.8     
Accepted name: 4-hydroxy-tetrahydrodipicolinate reductase
Reaction: (S)-2,3,4,5-tetrahydropyridine-2,6-dicarboxylate + NAD(P)+ + H2O = (2S,4S)-4-hydroxy-2,3,4,5-tetrahydrodipicolinate + NAD(P)H + H+
Glossary: (2S,4S)-4-hydroxy-2,3,4,5-tetrahydrodipicolinate = (2S,4S)-4-hydroxy-2,3,4,5-tetrahydropyridine-2,6-dicarboxylate
(S)-2,3,4,5-tetrahydropyridine-2,6-dicarboxylate = (2S)-2,3,4,5-tetrahydrodipicolinate
Other name(s): dihydrodipicolinate reductase (incorrect); dihydrodipicolinic acid reductase (incorrect); 2,3,4,5-tetrahydrodipicolinate:NAD(P)+ oxidoreductase (incorrect); dapB (gene name)
Systematic name: (S)-2,3,4,5-tetrahydropyridine-2,6-dicarboxylate:NAD(P)+ 4-oxidoreductase
Comments: The substrate of the enzyme was initially thought to be (S)-2,3-dihydrodipicolinate [1], and the enzyme was classified accordingly as EC 1.3.1.26, dihydrodipicolinate reductase. Later studies of the enzyme from the bacterium Escherichia coli have suggested that the actual substrate of the enzyme is (2S,4S)-4-hydroxy-2,3,4,5-tetrahydrodipicolinate, and that its activity includes a dehydration step [2], and thus the enzyme has been reclassified as 4-hydroxy-tetrahydrodipicolinate reductase. However, the identity of the substrate is still controversial, as more recently it has been suggested that it may be (S)-2,3-dihydrodipicolinate after all [3].
References:
1.  Farkas, W. and Gilvarg, C. The reduction step in diaminopimelic acid biosynthesis. J. Biol. Chem. 240 (1965) 4717–4722. [PMID: 4378965]
2.  Devenish, S.R., Blunt, J.W. and Gerrard, J.A. NMR studies uncover alternate substrates for dihydrodipicolinate synthase and suggest that dihydrodipicolinate reductase is also a dehydratase. J. Med. Chem. 53 (2010) 4808–4812. [PMID: 20503968]
3.  Karsten, W.E., Nimmo, S.A., Liu, J. and Chooback, L. Identification of 2,3-dihydrodipicolinate as the product of the dihydrodipicolinate synthase reaction from Escherichia coli. Arch. Biochem. Biophys. 653 (2018) 50–62. [PMID: 29944868]
[EC 1.17.1.8 created 1976 as EC 1.3.1.26, transferred 2013 to EC 1.17.1.8, modified 2020]
 
 
EC 2.3.1.89     
Accepted name: tetrahydrodipicolinate N-acetyltransferase
Reaction: acetyl-CoA + (S)-2,3,4,5-tetrahydropyridine-2,6-dicarboxylate + H2O = CoA + L-2-acetamido-6-oxoheptanedioate
Other name(s): tetrahydrodipicolinate acetylase; tetrahydrodipicolinate:acetyl-CoA acetyltransferase; acetyl-CoA:L-2,3,4,5-tetrahydrodipicolinate N2-acetyltransferase; acetyl-CoA:(S)-2,3,4,5-tetrahydropyridine-2,6-dicarboxylate 2-N-acetyltransferase
Systematic name: acetyl-CoA:(S)-2,3,4,5-tetrahydropyridine-2,6-dicarboxylate N2-acetyltransferase
References:
1.  Chatterjee, S.P. and White, P.J. Activities and regulation of the enzymes of lysine biosynthesis in a lysine-excreting strain of Bacillus megaterium. J. Gen. Microbiol. 128 (1982) 1073–1081.
[EC 2.3.1.89 created 1986]
 
 
EC 2.3.1.117     
Accepted name: 2,3,4,5-tetrahydropyridine-2,6-dicarboxylate N-succinyltransferase
Reaction: succinyl-CoA + (S)-2,3,4,5-tetrahydropyridine-2,6-dicarboxylate + H2O = CoA + N-succinyl-L-2-amino-6-oxoheptanedioate
Glossary: dipicolinate = pyridine-2,6-dicarboxylate
Other name(s): tetrahydropicolinate succinylase; tetrahydrodipicolinate N-succinyltransferase; tetrahydrodipicolinate succinyltransferase; succinyl-CoA:tetrahydrodipicolinate N-succinyltransferase; succinyl-CoA:2,3,4,5-tetrahydropyridine-2,6-dicarboxylate N-succinyltransferase
Systematic name: succinyl-CoA:(S)-2,3,4,5-tetrahydropyridine-2,6-dicarboxylate N-succinyltransferase
Comments: Involved in the biosynthesis of lysine in bacteria (including cyanobacteria) and higher plants. The 1992 edition of the Enzyme List erroneously gave the name 2,3,4,5-tetrahydropyridine-2-carboxylate N-succinyltransferase to this enzyme.
References:
1.  Simms, S.A., Voige, W.H. and Gilvarg, C. Purification and characterization of succinyl-CoA: tetrahydrodipicolinate N-succinyltransferase from Escherichia coli. J. Biol. Chem. 259 (1984) 2734–2741. [PMID: 6365916]
[EC 2.3.1.117 created 1989, modified 2001]
 
 
EC 2.6.1.83     
Accepted name: LL-diaminopimelate aminotransferase
Reaction: LL-2,6-diaminoheptanedioate + 2-oxoglutarate = (S)-2,3,4,5-tetrahydropyridine-2,6-dicarboxylate + L-glutamate + H2O
Glossary: LL-diaminopimelate = LL-2,6-diaminoheptanedioate
tetrahydrodipicolinate = tetrahydropyridine-2,6-dicarboxylate
Other name(s): LL-diaminopimelate transaminase; LL-DAP aminotransferase; LL-DAP-AT
Systematic name: LL-2,6-diaminoheptanedioate:2-oxoglutarate aminotransferase
Comments: A pyridoxal-phosphate enzyme. In vivo, the reaction occurs in the opposite direction to that shown above. This is one of the final steps in the lysine-biosynthesis pathway of plants (ranging from mosses to flowering plants). meso-Diaminoheptanedioate, an isomer of LL-2,6-diaminoheptanedioate, and the structurally related compounds lysine and ornithine are not substrates. 2-Oxoglutarate cannot be replaced by oxaloacetate or pyruvate. It is not yet known if the substrate of the biosynthetic reaction is the cyclic or acyclic form of tetrahydropyridine-2,6-dicarboxylate.
References:
1.  Hudson, A.O., Singh, B.K., Leustek, T. and Gilvarg, C. An LL-diaminopimelate aminotransferase defines a novel variant of the lysine biosynthesis pathway in plants. Plant Physiol. 140 (2006) 292–301. [PMID: 16361515]
[EC 2.6.1.83 created 2006]