Vitamin B6 biosynthesis: formation of pyridoxine 5′‐phosphate from 4‐(phosphohydroxy)‐l‐threonine and 1‐deoxy‐d‐xylulose‐5‐phosphate by PdxA and PdxJ protein

FEBS Letters

Maurer, Wolfgang¹  Laber, Bernd¹  Stepusin, Karin¹  Scharf, Sandra¹  Schmidt, Frank S¹ 

[1] Hoechst Schering AgrEvo GmbH, Biochemical Research, Werk Höchst, H872N, D-65926 Frankfurt am Main, Germany

关键词: 1-Deoxy-d-xylulose-5-phosphate;    Pyridoxal 5′-phosphate;    Pyridoxine 5′-phosphate;    PdxJ;    Vitamin B6;    DXP;    1-deoxy-d-xylulose-5-phosphate;    HTP;    4-(phosphohydroxy)-l-threonine;    PN;    pyridoxine;    PLP;    pyridoxal 5′-phosphate;    PNP;    pyridoxine 5′-phosphate;   

DOI  :  10.1016/S0014-5793(99)00393-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

In Escherichia coli the coenzyme pyridoxal 5′-phosphate (PLP) is synthesised de novo by a pathway that is thought to involve the condensation of 4-(phosphohydroxy)-l-threonine and 1-deoxy-d-xylulose, catalysed by the enzymes PdxA and PdxJ, to form either pyridoxine (vitamin B₆) or pyridoxine 5′-phosphate (PNP). Here we show that incubation of PdxJ with PdxA, 4-(phosphohydroxy)-l-threonine, NAD and 1-deoxy-d-xylulose-5-phosphate, but not 1-deoxy-d-xylulose, results in the formation of PNP. The PNP formed was characterised by (i) cochromatography with an authentic standard, (ii) conversion to pyridoxine by alkaline phosphatase treatment, and (iii) UV and fluorescence spectroscopy. Furthermore, when [2-¹⁴C]1-deoxy-d-xylulose-5-phosphate was used as a substrate, the radioactivity was incorporated into PNP. These results clarify the previously unknown role of PdxJ in the de novo PLP biosynthetic pathway. The sugar used as substrate by PdxJ is 1-deoxy-d-xylulose-5-phosphate rather than the previously assumed 1-deoxy-d-xylulose. The first vitamin B₆ vitamer synthesised is PNP, and not pyridoxine.

【 授权许可】

Unknown