Pathways & interactions
Pyridoxal phosphate-dependent transferase, major region, subdomain 1 (IPR015421)
Short name: PyrdxlP-dep_Trfase_major_sub1
Pyridoxal phosphate is the active form of vitamin B6 (pyridoxine or pyridoxal). Pyridoxal 5'-phosphate (PLP) is a versatile catalyst, acting as a coenzyme in a multitude of reactions, including decarboxylation, deamination and transamination [PMID: 8690703, PMID: 7748903, PMID: 15189147]. PLP-dependent enzymes are primarily involved in the biosynthesis of amino acids and amino acid-derived metabolites, but they are also found in the biosynthetic pathways of amino sugars and in the synthesis or catabolism of neurotransmitters; pyridoxal phosphate can also inhibit DNA polymerases and several steroid receptors [PMID: 17109392]. Inadequate levels of pyridoxal phosphate in the brain can cause neurological dysfunction, particularly epilepsy [PMID: 16763894].
PLP enzymes exist in their resting state as a Schiff base, the aldehyde group of PLP forming a linkage with the epsilon-amino group of an active site lysine residue on the enzyme. The alpha-amino group of the substrate displaces the lysine epsilon-amino group, in the process forming a new aldimine with the substrate. This aldimine is the common central intermediate for all PLP-catalysed reactions, enzymatic and non-enzymatic [PMID: 15581583].
This entry represents subdomain 1 of the major region of PLP-dependent transferases. This domain has a 3-layer alpha/beta/alpha sandwich topology. The major region can be found in the following PLP-dependent transferase families:
- Aspartate aminotransferase (AAT)-like enzymes, such as aromatic aminoacid aminotransferase AroAT, glutamine aminotransferase and kynureninase [PMID: 17300176].
- Beta-eliminating lyases, such as tyrosine phenol lyase and tryptophanase [PMID: 16790938].
- Pyridoxal-dependent decarboxylases, such as DOPA decarboxylase and glutamate decarboxylase beta (GadB) [PMID: 15690345].
- Cystathionine synthase-like enzymes, such as cystalysin, methionine gamma-lyase (MGL), and cysteine desulphurase (IscS) [PMID: 17014820].
- GABA-aminotransferase-like enzymes, such as ornithine aminotransferase and serine hydroxymethyltransferase [PMID: 15848278].
- Ornithine decarboxylase major domain [PMID: 10666573].
- G3DSA:3.40.640.10 (G3DSA:3.40.640.10)