Characterization of a novel bifunctional dihydropteroate synthase/dihydropteroate reductase enzyme from Helicobacter pylori

Itay Levin, Moshe Mevarech*, Bruce A. Palfey

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Tetrahydrofolate is a ubiquitous C1 carrier in many biosynthetic pathways in bacteria, importantly, in the biosynthesis of formylmethionyl tRNAfMet, which is essential for the initiation of translation. The final step in the biosynthesis of tetrahydrofolate is carried out by the enzyme dihydrofolate reductase (DHFR). A search of the complete genome sequence of Helicobacter pylori failed to reveal any sequence that encodes DHFR. Previous studies demonstrated that the H. pylori dihydropteroate synthase gene folP can complement an Escherichia coli strain in which folA and folM, encoding two distinct DHFRs, are deleted. It was also shown that H. pylori FolP possesses an additional N-terminal domain that binds flavin mononucleotide (FMN). Homologous domains are found in FolP proteins of other microorganisms that do not possess DHFR. In this study, we demonstrated that H. pylori FolP is also a dihydropteroate reductase that derives its reducing power from soluble flavins, reduced FMN and reduced flavin adenine dinucleotide. We also determined the stoichiometry of the enzyme-bound flavin and showed that half of the bound flavin is exchangeable with the soluble flavins. Finally, site-directed mutagenesis of the most conserved amino acid residues in the N-terminal domain indicated the importance of these residues for the activity of the enzyme as a dihydropteroate reductase.

Original languageEnglish
Pages (from-to)4062-4069
Number of pages8
JournalJournal of Bacteriology
Volume189
Issue number11
DOIs
StatePublished - Jun 2007

Funding

FundersFunder number
National Institute of General Medical SciencesR01GM061087

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