The "Super Mutant" of Yeast FMN Adenylyltransferase Enhances the Enzyme Turnover Rate by Attenuating Product Inhibition

Biochemistry. 2013 May 28;52(21):3615-7. doi: 10.1021/bi400454w. Epub 2013 May 15.

Abstract

FMN adenylyltransferase (FMNAT) is an essential enzyme catalyzing the last step of a two-step pathway converting riboflavin (vitamin B2) to FAD, the ubiquitous flavocoenzyme. A structure-based mutagenesis and steady-state kinetic analysis of yeast FMNAT unexpectedly revealed that mutant D181A had a much faster turnover rate than the wild-type enzyme. Product inhibition analysis showed that wild-type FMNAT is strongly inhibited by FAD, whereas the D181A mutant has an attenuated product inhibition. These results provide a structural basis for the product inhibition of the enzyme and suggest that product release may be the rate-limiting step of the reaction.

Publication types

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

MeSH terms

  • Biocatalysis
  • Flavin Mononucleotide / antagonists & inhibitors
  • Flavin Mononucleotide / metabolism
  • Kinetics
  • Mutagenesis
  • Nucleotidyltransferases / genetics
  • Nucleotidyltransferases / metabolism*
  • Saccharomyces cerevisiae / enzymology*

Substances

  • Flavin Mononucleotide
  • Nucleotidyltransferases
  • FMN adenylyltransferase