Evidence for substrate assisted catalysis in N-acetylphosphoglucosamine mutase

Olawale G. Raimi, Ramón Hurtado Guerrero, Daan M. F. van Aalten (Lead / Corresponding author)

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Abstract

N -acetylphosphoglucosamine mutase (AGM1) is a key component of the hexosamine biosynthetic pathway that produces UDP-GlcNAc, an essential precursor for a wide range of glycans in eukaryotes. AGM belongs to the a-D-phosphohexomutase metalloenzyme superfamily and catalyses the interconversion of N -acetylglucosamine-6-phosphate (GlcNAc-6P) to N -acetylglucosamine-1-phosphate (GlcNAc-1P) through N -acetylglucosamine-1,6-bisphosphate (GlcNAc-1,6-bisP) as the catalytic intermediate. Although there is an understanding of the phosphoserine-dependent catalytic mechanism at enzymatic and structural level, the identity of the requisite catalytic base in AGM1/phosphoglucomutases is as yet unknown. Here we present crystal structures of a Michaelis complex of AGM1 with GlcNAc-6P and Mg2+, and a complex of the inactive Ser69Ala mutant together with glucose-1,6-bisphosphate (Glc-1,6-bisP) that represent key snapshots along the reaction coordinate. Together with mutagenesis, these structures reveal that the phosphate group of the hexose-1,6-bisP intermediate may act as the catalytic base.

Original languageEnglish
Pages (from-to)2547-2557
Number of pages11
JournalThe Biochemical journal
Volume475
Issue number15
Early online date2 Jul 2018
DOIs
Publication statusPublished - 16 Aug 2018

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Keywords

  • phosphohexomutase
  • catalysis
  • Aspergillus fumigatus
  • Reaction mechanism

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