Expression, crystallization and activities of the two family 11 aldo-keto reductases from Bacillus subtilis.

Two members of the aldo-keto reductase family 11 from Bacillus subtilis have been crystallized and their oxidoreductase activity confirmed. AKR11A is a protein induced by inositol and repressed by glucose. AKR11B is induced when the cell is stressed by heat, acid, ethanol, starvation or osmotic shock and is therefore classified as a general stress protein. The expected NADPH-dependent sugar reductase activities for both proteins have been confirmed kinetically with several substrates. AKR11B exhibited typical aldo-keto reductase kinetics. However, only trace activity was found in AKR11A. To examine the effects of differences in sequence on the structures and functions of these enzymes, a crystallographic study has been initiated. AKR11A has been crystallized in its apo form and AKR11B crystals were obtained in complex with NADP(+).