Structure of Escherichia coli pyridoxine 5'-phosphate oxidase in a tetragonal crystal form: insights into the mechanistic pathway of the enzyme

Acta Crystallogr D Biol Crystallogr. 2005 May;61(Pt 5):599-604. doi: 10.1107/S0907444905005512. Epub 2005 Apr 20.


Escherichia coli pyridoxine 5'-phosphate oxidase (ePNPOx) catalyzes the terminal step in the biosynthesis of pyridoxal 5'-phosphate (PLP) by the FMN oxidation of pyridoxine 5'-phosphate (PNP) or pyridoxamine 5'-phosphate (PMP), forming FMNH(2) and H(2)O(2). The crystal structure of ePNPOx is reported in a tetragonal unit cell at 2.6 A resolution. The three-dimensional fold of this structure is very similar to those of the E. coli and human enzymes that crystallized in trigonal and monoclinic unit cells. However, unlike the previous structures, the tetragonal structure shows major disorder in one of the two subunit domains that has opened up both the active site and a putative tunnel. Comparison of these structures gives an insight into the mechanistic pathway of PNPOx: from the resting enzyme with no substrate bound, to the initial binding of the substrate at the active site, to the catalytic stage and to the release of the catalytic product from the active site.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Apoenzymes / chemistry
  • Binding Sites
  • Catalysis
  • Crystallization
  • Crystallography, X-Ray
  • Escherichia coli / enzymology*
  • Models, Molecular
  • Pyridoxaminephosphate Oxidase / chemistry*
  • Vitamin B 6 / chemistry


  • Apoenzymes
  • Vitamin B 6
  • Pyridoxaminephosphate Oxidase