Crystal structure of a Bombyx mori sigma-class glutathione transferase exhibiting prostaglandin E synthase activity |
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Authors: | Kohji Yamamoto Akifumi Higashiura Mamoru Suzuki Kosuke Aritake Yoshihiro Urade Nobuko Uodome Atsushi Nakagawa |
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Institution: | 1. Faculty of Agriculture, Kyushu University Graduate School, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan;2. Institute for Protein Research, Osaka University, Suita 565-0871, Japan;3. Department of Molecular Behavioral Biology, Osaka Bioscience Institute, 6-2-4, Furuedai, Suita, Osaka 565-0874, Japan |
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Abstract: | BackgroundGlutathione transferases (GSTs) are members of a major family of detoxification enzymes. Here, we report the crystal structure of a sigma-class GST of Bombyx mori, bmGSTS1, to gain insight into the mechanism catalysis.MethodsThe structure of bmGSTS1 and its complex with glutathione were determined at resolutions of 1.9 Å and 1.7 Å by synchrotron radiation and the molecular replacement method.ResultsThe three-dimensional structure of bmGSTS1 shows that it exists as a dimer and is similar in structure to other GSTs with respect to its secondary and tertiary structures. Although striking similarities to the structure of prostaglandin D synthase were also detected, we were surprised to find that bmGSTS1 can convert prostaglandin H2 into its E2 form. Comparison of bmGSTS1 with its glutathione complex showed that bound glutathione was localized to the glutathione-binding site (G-site). Site-directed mutagenesis of bmGSTS1 mutants indicated that amino acid residues Tyr8, Leu14, Trp39, Lys43, Gln50, Met51, Gln63, and Ser64 in the G-site contribute to catalytic activity.ConclusionWe determined the tertiary structure of bmGSTS1 exhibiting prostaglandin E synthase activity.General significanceThese results are, to our knowledge, the first report of a prostaglandin synthase activity in insects. |
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Keywords: | GSH glutathione GST glutathione transferase GSTS sigma-class GST PG prostaglandin PGDS prostaglandin D synthase PGES prostaglandin E synthase SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis |
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