ExplorEnz: EC 4.3.3.7

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4.3.3.7

Accepted name:

4-hydroxy-tetrahydrodipicolinate synthase

Reaction:

pyruvate + L-aspartate-4-semialdehyde = (2S,4S)-4-hydroxy-2,3,4,5-tetrahydrodipicolinate + H₂O

For diagram of lysine biosynthesis (early stages), click here

Glossary:

(2S,4S)-4-hydroxy-2,3,4,5-tetrahydrodipicolinate = (2S,4S)-4-hydroxy-2,3,4,5-tetrahydropyridine-2,6-dicarboxylate

Other name(s):

dihydrodipicolinate synthase (incorrect); dihydropicolinate synthetase (incorrect); dihydrodipicolinic acid synthase (incorrect); L-aspartate-4-semialdehyde hydro-lyase (adding pyruvate and cyclizing); dapA (gene name).

Systematic name:

L-aspartate-4-semialdehyde hydro-lyase [adding pyruvate and cyclizing; (4S)-4-hydroxy-2,3,4,5-tetrahydro-(2S)-dipicolinate-forming]

Comments:

The reaction can be divided into three consecutive steps: Schiff base formation with pyruvate, the addition of L-aspartate-semialdehyde, and finally transimination leading to cyclization with simultaneous dissociation of the product. The product of the enzyme was initially thought to be (S)-2,3-dihydrodipicolinate [1,2], and the enzyme was classified accordingly as EC 4.2.1.52, dihydrodipicolinate synthase. Later studies of the enzyme from the bacterium Escherichia coli have suggested that the actual product of the enzyme is (2S,4S)-4-hydroxy-2,3,4,5-tetrahydrodipicolinate [3], and thus the enzyme has been reclassified as 4-hydroxy-tetrahydrodipicolinate synthase. However, the identity of the product is still controversial, as more recently it has been suggested that it may be (S)-2,3-dihydrodipicolinate after all [5].

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc, PDB

References:

1.	Yugari, Y. and Gilvarg, C. The condensation step in diaminopimelate synthesis. J. Biol. Chem. 240 (1965) 4710–4716. [PMID: 5321309]
2.	Blickling, S., Renner, C., Laber, B., Pohlenz, H.D., Holak, T.A. and Huber, R. Reaction mechanism of Escherichia coli dihydrodipicolinate synthase investigated by X-ray crystallography and NMR spectroscopy. Biochemistry 36 (1997) 24–33. [DOI] [PMID: 8993314]
3.	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. [DOI] [PMID: 20503968]
4.	Soares da Costa, T.P., Muscroft-Taylor, A.C., Dobson, R.C., Devenish, S.R., Jameson, G.B. and Gerrard, J.A. How essential is the ’essential’ active-site lysine in dihydrodipicolinate synthase. Biochimie 92 (2010) 837–845. [DOI] [PMID: 20353808]
5.	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 4.3.3.7 created 1972 as EC 4.2.1.52, transferred 2012 to EC 4.3.3.7, modified 2020]