Structure-guided activity restoration of the silkworm glutathione transferase Omega GSTO3-3 |
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| Authors: | Chen Bao-Yu Ma Xiao-Xiao Guo Peng-Chao Tan Xiang Li Wei-Fang Yang Jie-Pin Zhang Nan-Nan Chen Yuxing Xia Qingyou Zhou Cong-Zhao |
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| Institution: | 1 School of Life Sciences and Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230027, People's Republic of China2 Key Sericultural Laboratory of Agricultural Ministry, Institute of Sericulture and Systems Biology, Southwest University, Chongqing 400716, China |
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| Abstract: | Glutathione transferases (GSTs) are ubiquitous detoxification enzymes that conjugate hydrophobic xenobiotics with reduced glutathione. The silkworm Bombyx mori encodes four isoforms of GST Omega (GSTO), featured with a catalytic cysteine, except that bmGSTO3-3 has an asparagine substitution of this catalytic residue. Here, we determined the 2.20-Å crystal structure of bmGSTO3-3, which shares a typical GST overall structure. However, the extended C-terminal segment that exists in all the four bmGSTOs occupies the G-site of bmGSTO3-3 and makes it unworkable, as shown by the activity assays. Upon mutation of Asn29 to Cys and truncation of the C-terminal segment, the in vitro GST activity of bmGSTO3-3 could be restored. These findings provided structural insights into the activity regulation of GSTOs. |
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| Keywords: | Bombyx mori glutathione transferase Omega crystal structure site-directed mutagenesis enzymatic activity |
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