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 , 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 .
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SYSTEMATIC NAME
IUBMB Comments
L-aspartate-4-semialdehyde hydro-lyase [adding pyruvate and cyclizing; (4S)-4-hydroxy-2,3,4,5-tetrahydro-(2S)-dipicolinate-forming]
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].
lysine insensitivity of dihydrodipicolinate synthase analyzed, catalytic lysine residue forms a Schiff base adduct with pyruvate, active site lysine residues (K176a, K176b)
mutagenesis of the lysine binding sites of the Corynebacterium glutamicum enzyme according to the residues in the Escherichia coli enzyme does not conver the expected feedback inhibition but an activation of the enzyme by L-lysine
reaction mixture includes 100 mM Tris-HCl, 2.5 mM pyruvate, 0.05-0.1 microg dihydrodipicolinate synthase and 0.2 mM NADPH, from 5.6 to 22.4 mM plots deviate from typical Michaelis-Menten kinetics, increased concentration fits an uncompetitive substrate inhibition model
structure in vicinity of the putative binding site for S-lysine indicates that the allosteric binding site in the Escherichia coli dihydrodipicolinate synthase does not exist in the enzyme of Corynebacterium glutamicum, difference of three non-conservative amino acids substitutions, explains lack of feedback inhibition by lysine in Corynebacterium glutamicum
structure in vicinity of the putative binding site for S-lysine indicates that the allosteric binding site in the Escherichia coli dihydrodipicolinate synthase does not exist in the enzyme of Corynebacterium glutamicum, difference of three non-conservative amino acids substitutions, explains lack of feedback inhibition by lysine in Corynebacterium glutamicum
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
hanging drop method, data collection and refinement statistics, refinement resolution originally extended to 3.0 A, gradually increased to 2.5 A, and finally to 2.2 A, structural similarities to other dihydrodipicolinate synthase
mutagenesis of the lysine binding sites of the Corynebacterium glutamicum enzyme according to the residues in the Escherichia coli enzyme does not conver the expected feedback inhibition but an activation of the nezyme by L-lysine
Exploring the allosteric mechanism of dihydrodipicolinate synthase by reverse engineering of the allosteric inhibitor binding sites and its application for lysine production