1.1.1.262 4-(phosphonooxy)threonine + NAD(P)+ fourth step of the pyridoxal 5'-phosphate biosynthesis Escherichia coli 2-amino-3-oxo-4-phosphonooxybutyrate + NAD(P)H - 370799 1.1.1.262 4-(phosphonooxy)threonine + NAD(P)+ i.e. 4-hydroxy-L-threonine phosphate or HTP, enzyme strictly requires the phosphate ester form of the substrate, interaction between enzyme and substrate via phosphate group, step 1 of the overall reaction Escherichia coli 2-amino-3-oxo-4-phosphonooxybutyrate + NAD(P)H reaction intermediate 370799 1.1.1.262 4-(phosphonooxy)threonine + NAD(P)+ i.e. 4-hydroxy-L-threonine-4-phosphate, HTP Escherichia coli 3-amino-1-hydroxyacetone 1-phosphate + CO2 + NAD(P)H i.e. AHAB, primary product of the reaction, no formation of 2-amino-3-oxo-4-phosphonooxybutyrate as intermediate is detected, identification by electrospray ionization mass spectrometry 370800 1.1.1.262 4-(phosphohydroxy)-L-threonine + NAD+ involved in pyridoxal 5'-phosphate formation Escherichia coli 2-amino-3-oxo-4-phosphohydroxybutyrate + NADH further condensation with 1-deoxy-D-xylulose-5-phosphate to form pyridoxal 5'-phosphate 139544 1.1.1.262 4-(phosphohydroxy)-L-threonine + NAD+ involved in pyridoxal 5'-phosphate formation Escherichia coli 2-amino-3-oxo-4-phosphohydroxybutyrate + NADH undergoes decarboxylation either catalysed by the enzyme or after release, further formation of pyridoxal 5'-phosphate catalysed by PdxJ protein 139544 1.1.1.262 4-(phosphohydroxy)-L-threonine + NAD+ involved in pyridoxal 5'-phosphate formation Escherichia coli 3-phosphohydroxy-1aminoacetone + CO2 + NADH + H+ further condensation with 1-deoxy-D-xylulose-5-phosphate to form pyridoxal 5'-phosphate 139545 1.1.1.262 4-(phosphonooxy)threonine + NAD(P)+ involved in the biosynthesis of vitamin B6 Escherichia coli 3-amino-1-hydroxyacetone 1-phosphate + CO2 + NAD(P)H - 370800 1.1.1.262 2-amino-3-oxo-4-phosphonooxybutyrate + H2O step 2 of the overall reaction Escherichia coli 3-amino-1-hydroxyacetone 1-phosphate + CO2 i.e. AHAP 371620