Cloning, expression, purification, crystallization and preliminary X-ray studies of a pyridoxine 5'-­phosphate oxidase from Mycobacterium smegmatis

Pyridoxine 5'-phosphate oxidases (PNPOxs) are known to catalyse the terminal step in pyridoxal 5'-phosphate biosynthesis in a flavin mononucleotide-dependent manner in humans and Escherichia coli. Recent reports of a putative PNPOx from Mycobacterium tuberculosis, Rv1155, suggest that the cofactor or catalytic mechanism may differ in Mycobacterium species. To investigate this, a putative PNPOx from M. smegmatis, Msmeg_3380, has been cloned. This enzyme has been recombinantly expressed in E. coli and purified to homo­geneity. Good-quality crystals of selenomethionine-substituted Msmeg_3380 were obtained by the hanging-drop vapour-diffusion technique and diffracted to 1.2 Å using synchrotron radiation.