title: 4-O-phosphoryl-L-threonine, a substrate of the pdxC(serC) gene product involved in vitamin B6 biosynthesis.
abstract: The Escherichia coli pdxC(serC) gene codes for a transaminase (EC 2.6.1.52). The gene is involved in both pyridoxine (vitamin B6) and serine biosynthesis and was overexpressed as a MalE/PdxC(SerC) fusion protein. The fusion protein was purified by affinity chromatography on an amylose resin and hydrolyzed in the presence of protease factor Xa. Both the fusion protein and the PdxC(SerC) protein were characterized (K(M) value, turnover number, optimum pH). Both enzymes used 4-O-phosphoryl-L-threonine rather than 4-hydroxy-L-threonine as a substrate indicating that the phosphorylated rather than the non-phosphorylated amino acid is involved in pyridoxine biosynthesis. Pyridoxal phosphate was shown to be the cofactor for both enzymes and therefore seems to be involved in its own biosynthesis.
authors.affiliation: Institut für Pharmazeutische Biologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Drewke
authors.forename: M
authors.initials: M
authors.lastname: Klein
authors.forename: D
authors.initials: D
authors.lastname: Clade
authors.forename: A
authors.initials: A
authors.lastname: Arenz
authors.forename: R
authors.initials: R
authors.lastname: Müller
authors.forename: E
authors.initials: E
authors.lastname: Leistner
mesh_terms: D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008954:Models, Biological; D008969:Molecular Sequence Data; D011732:Pyridoxal Phosphate / Q000378:metabolism; D011736:Pyridoxine / Q000096:biosynthesis*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D013912:Threonine / Q000031:analogs & derivatives* / Q000378:metabolism; D000637:Transaminases / Q000235:genetics / Q000378:metabolism*
chemical_list: C100760:4-O-phosphorylthreonine; D017931:DNA Primers; D004269:DNA, Bacterial; D011993:Recombinant Fusion Proteins; D013912:Threonine; D011732:Pyridoxal Phosphate; D000637:Transaminases; C022393:phosphoserine aminotransferase; D011736:Pyridoxine