| Type: | Family | Name: | Aspartate kinase, monofunctional class |
| Description: | Aspartate kinase catalyzes the first step in the biosynthesis of Lys (via its precursor diaminopimelate), Met, and Thr. In Escherichia coli, a distinct isozyme is inhibited by each of these three amino acid end products []. The Met-sensitive (I) and Thr-sensitive (II) forms are bifunctional enzymes fused to homoserine dehydrogenase, which catalyses the next step in the biosynthesis of these amino acids. Inn contrast, the Lys-sensitive form (III) is a monofunctional enzyme; homoserine dehydrogenase is not part of the Lys biosynthetic pathway.This entry describes a subclass of the aspartate kinases that are mostly Lys-sensitive and are not fused to homoserine dehydrogenase. The E. coli enzyme is a homodimer, while the Bacillus and Corynebacterium enzymes are alpha 2/beta 2 heterotetramers, where the beta subunit is translated from an in-phase alternative initiator at Met-246 [, ]. The protein slr0657 from Synechocystis PCC6803 is extended by a duplication of the C-terminal region corresponding to the beta chain. Incorporation of a second copy of the C-terminal domain may be quite common in this subgroup of aspartokinases. | Short Name: | Asp_kin_monofn |
