Department of Bioscience and Biotechnology, Kyushu University^* Department of Biochemistry and Bioscience, Miyazaki University, Japan^**
○Takamasa Teramoto^* Kanako Inada^* Youichi Sakakibara^** Masahito Suiko^** Makoto Kimura^* Yoshimitsu Kakuta^*

The cytosolic sulfotransferase (SULT) transfer the sulfate group from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to a wild variety of endogenous and exogenous phenolic substrate, such as steroid hormones, thyroid hormones, drug, and xenobiotics. Mouse SULT1D1 is active toward small phenolic, and amine-containing molecules, but not active toward steroid or thyroid hormone. The mechanism is proposed to proceed via an S_N2 nucleophilic attack of the OH group of phenoll on the Sulfonate of PAPS through the direct in-line transition state. In this study, we have performed x-ray crystallographic structural analysis to reveal structural basis of a direct in-line sulfonic transfer mechanism of SULT1D1.
The crystals of SULT1D1 were obtained in presence of the substrate donor product 3'-phosphoadenosine 5'-phosphate (PAP). This obtained crystal was proceeded to soak in p-nitrophenyl sulfate solution to cause reverse reaction from PAP to PAPS. Finally the crystal containg PAPS was soak in p-nitrophenol (PNP) for 30 seconds. The crystal structure of mouse SULT1D1 has determined by molecular replacement using mouse SULT1E1 and has been refined to 1.7Å. In the result, we observed that PAPS interacts with PAPS binding motif which is conserved region in sulfotransferases and PNP bind at active site. Consequently, we observed ES complex structure of mSULT1D1.