Download MendeleyStructural and Biophysical Characterization of Human myo-Inositol Oxygenase
Thorsell, A.G., Persson, C., Voevodskaya, N., Busam, R.D., Hammarstrom, M., Graslund, S., Graslund, A., Hallberg, B.M.(2008) J Biol Chem 283: 15209-15216
- PubMed: 18364358
- DOI: https://doi.org/10.1074/jbc.M800348200
- Primary Citation of Related Structures:
2IBN, 3BXD - PubMed Abstract:
Altered inositol metabolism is implicated in a number of diabetic complications. The first committed step in mammalian inositol catabolism is performed by myo-inositol oxygenase (MIOX), which catalyzes a unique four-electron dioxygen-dependent ring cleavage of myo-inositol to D-glucuronate. Here, we present the crystal structure of human MIOX in complex with myo-inosose-1 bound in a terminal mode to the MIOX diiron cluster site. Furthermore, from biochemical and biophysical results from N-terminal deletion mutagenesis we show that the N terminus is important, through coordination of a set of loops covering the active site, in shielding the active site during catalysis. EPR spectroscopy of the unliganded enzyme displays a two-component spectrum that we can relate to an open and a closed active site conformation. Furthermore, based on site-directed mutagenesis in combination with biochemical and biophysical data, we propose a novel role for Lys(127) in governing access to the diiron cluster.
Organizational Affiliation:
Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
