Catalysis of an Essential Step in Vitamin B2 Biosynthesis by a Consortium of Broad Spectrum Hydrolases

Chembiochem. 2015 Nov;16(17):2466-9. doi: 10.1002/cbic.201500352. Epub 2015 Sep 25.

Abstract

An enzyme catalysing the essential dephosphorylation of the riboflavin precursor, 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione 5'-phosphate (6), was purified about 800-fold from a riboflavin-producing Bacillus subtilis strain, and was assigned as the translation product of the ycsE gene by mass spectrometry. YcsE is a member of the large haloacid dehalogenase (HAD) superfamily. The recombinant protein was expressed in Escherichia coli. It catalyses the hydrolysis of 6 (vmax , 12 μmol mg(-1) min(-1) ; KM , 54 μm) and of FMN (vmax , 25 μmol mg(-1) min(-1) ; KM , 135 μm). A ycsE deletion mutant of B. subtilis was not riboflavin dependent. Two additional proteins (YwtE, YitU) that catalyse the hydrolysis of 6 at appreciable rates were identified by screening 13 putative HAD superfamily members from B. subtilis. The evolutionary processes that have resulted in the handling of an essential step in the biosynthesis of an essential cofactor by a consortium of promiscuous enzymes require further analysis.

Keywords: biosynthesis; haloacid dehalogenase; hydrolases; isoenzymes; vitamin B2.

MeSH terms

  • Bacillus subtilis / enzymology
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Biocatalysis
  • Escherichia coli / metabolism
  • Hydrolases / genetics
  • Hydrolases / metabolism
  • Hydrolysis
  • Isoenzymes / genetics
  • Isoenzymes / metabolism
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / genetics
  • Riboflavin / biosynthesis*
  • Riboflavin / chemistry

Substances

  • Bacterial Proteins
  • Isoenzymes
  • Recombinant Proteins
  • Hydrolases
  • 2-haloacid dehalogenase
  • Riboflavin