3INT

X-ray crystallography reveals a reduced substrate complex of UDP-galactopyranose mutase poised for covalent catalysis by flavin .

(2009) Biochemistry 48: 9171-9173

• PubMed: 19719175 Search on PubMedSearch on PubMed Central
• DOI: https://doi.org/10.1021/bi901437v
• Primary Citation of Related Structures:  
  3INR, 3INT


• PubMed Abstract: 
  

  The flavoenzyme uridine 5'-diphosphate galactopyranose mutase (UGM or Glf) catalyzes the interconversion of UDP-galactopyranose and UDP-galactofuranose. The latter is a key building block for cell wall construction in numerous pathogens, including Mycobacterium tuberculosis. Mechanistic studies of UGM suggested a novel role for the flavin, and we previously provided evidence that the catalytic mechanism proceeds through a covalent flavin-galactose iminium. Here, we describe 2.3 and 2.5 A resolution X-ray crystal structures of the substrate-bound enzyme in oxidized and reduced forms, respectively. In the latter, C1 of the substrate is 3.6 A from the nucleophilic flavin N5 position. This orientation is consistent with covalent catalysis by flavin.

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Organizational Affiliation: 

Department of Biochemistry, National Magnetic Resonance Facility at Madison, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.