<p>Dihydrodipicolinate reductase catalyzes the second step in the biosynthesis of diaminopimelic acid and lysine, the NAD or NADP-dependent reduction of 2,3-dihydrodipicolinate into 2,3,4,5-tetrahydrodipicolinate [<cite idref="PUB00019387"/>, <cite idref="PUB00019388"/>, <cite idref="PUB00000417"/>].</p><p>In <taxon tax_id="562">Escherichia coli</taxon> and <taxon tax_id="1773">Mycobacterium tuberculosis</taxon>, dihydrodipicolinate reductase has equal specificity for NADH and NADPH, however in <taxon tax_id="2336">Thermotoga maritima</taxon> there it has a greater affinity for NADPH [<cite idref="PUB00043321"/>]. In addition, the enzyme is inhibited by high concentrations of its substrate, which consequently acts as a feedback control on the lysine biosynthesis pathway. In T. maritima, the enzyme also lacks N-terminal and C-terminal loops which are present in enzyme of the former two organisms.</p><p>This entry represents the N-terminal domain of dihydrodipicolinate reductase which binds the dinucleotide NAD(P)H.</p>