Download MendeleyX-ray crystallography reveals a reduced substrate complex of UDP-galactopyranose mutase poised for covalent catalysis by flavin .
Gruber, T.D., Westler, W.M., Kiessling, L.L., Forest, K.T.(2009) Biochemistry 48: 9171-9173
- PubMed: 19719175
- 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.
Organizational Affiliation:
Department of Biochemistry, National Magnetic Resonance Facility at Madison, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
