title: Functional and mutational analyses of an omega-class glutathione S-transferase (GSTO2) that is required for reducing oxidative damage in Apis cerana cerana.
abstract: Glutathione S-transferases perform a variety of vital functions, particularly in reducing oxidative damage. Here, we investigated the expression patterns of Apis cerana cerana omega-class glutathione S-transferase 2 (AccGSTO2) under various stresses and explored its connection with antioxidant defences. We found that AccGSTO2 knockdown by RNA interference triggered increased mortality in Ap. cerana cerana, and immunohistochemistry revealed significantly decreased AccGSTO2 expression, particularly in the midgut and fat body. Further analyses indicated that AccGSTO2 knockdown resulted in decreases in catalase and glutathione reductase activities, ascorbate content and the ratio of reduced to oxidized glutathione, and increases in H2 O2 , malondialdehyde and carbonyl contents. We also analysed the transcripts of other antioxidant genes and found that many genes were down-regulated in the AccGSTO2 knockdown samples, revealing that AccGSTO2 may be indispensable for attaining a normal lifespan by enhancing cellular oxidative resistance. In addition, the roles of cysteine residues in AccGSTO2 were explored using site-directed mutagenesis. Mutants of Cys(28) and Cys(124) significantly affected the enzyme and antioxidant activities of AccGSTO2, which may be attributed to the changes in the spatial structures of mutants as determined by homology modelling. In summary, these observations provide novel insight into the structural and functional characteristics of GSTOs.
authors.affiliation: State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong, China.|School of Basic Medical Sciences, Taishan Medical University, Taian, Shandong, China.
authors.forename: Y-Y
authors.initials: YY
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong, China.
authors.forename: X-L
authors.initials: XL
authors.lastname: Guo
authors.affiliation: School of Basic Medical Sciences, Taishan Medical University, Taian, Shandong, China.
authors.forename: Y-L
authors.initials: YL
authors.lastname: Liu
authors.affiliation: College of Animal Science and Technology, Shandong Agricultural University, Taian, Shandong, China.
authors.forename: F
authors.initials: F
authors.lastname: Liu
authors.affiliation: College of Animal Science and Technology, Shandong Agricultural University, Taian, Shandong, China.
authors.forename: H-F
authors.initials: HF
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong, China.
authors.forename: X-Q
authors.initials: XQ
authors.lastname: Guo
authors.affiliation: College of Animal Science and Technology, Shandong Agricultural University, Taian, Shandong, China.
authors.forename: B-H
authors.initials: BH
authors.lastname: Xu
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001516:Bees / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D004252:DNA Mutational Analysis; D015870:Gene Expression; D005982:Glutathione Transferase / Q000235:genetics* / Q000378:metabolism; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D007814:Larva / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D018384:Oxidative Stress
chemical_list: D000975:Antioxidants; D019476:Insect Proteins; D005982:Glutathione Transferase
keywords: Apis cerana cerana; GSTO; RNA interference; antioxidant enzyme; site-directed mutagenesis