Structural studies of MIP synthase

The conversion of glucose 6-phosphate to 1-L-myo-inositol 1-phosphate (MIP) by 1-L-myo-inositol 1-phosphate synthase (MIP synthase) is the first commi tted and rate-limiting step in the de novo biosynthesis of inositol in all eukaryotes. The importance of inositol-containing molecules both as membran e components and as critical second messenger signal-transduction species m ake the function and regulation of this enzyme important for a host of biol ogically important cellular functions including proliferation, neurostimula tion, secretion and contraction. MIP synthase has been overexpressed in Esc herichia coli and purified to homogeneity by chromatographic methods. Two c rystal forms of MIP synthase were obtained by the hanging-drop vapor-diffus ion method. Native data sets far both crystal forms were collected in-house on a Rigaku R-AXIS IIC imaging-plate detector. Crystal form I belongs to s pace group C2, with unit-cell parameters a = 153.0, b = 96.6, c = 122.6 Ang strom, beta = 126.4 degrees, and diffracts to 2.5 Angstrom resolution. Crys tal form II belongs to space group P2(1), with unit-cell parameters a = 94. 5, b = 186.2, c = 86,5 Angstrom, beta = 110.5 degrees, and diffracts to 2.9 Angstrom resolution.