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Functional and mutational analyses of an omega‐class glutathione S ‐transferase ( GSTO2 ) that is required for reducing oxidative damage in Apis cerana cerana
Author(s) -
Zhang Y.Y.,
Guo X.L.,
Liu Y.L.,
Liu F.,
Wang H.F.,
Guo X.Q.,
Xu B.H.
Publication year - 2016
Publication title -
insect molecular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.955
H-Index - 93
eISSN - 1365-2583
pISSN - 0962-1075
DOI - 10.1111/imb.12236
Subject(s) - gene knockdown , biology , glutathione , apis cerana , antioxidant , glutathione reductase , glutathione s transferase , biochemistry , catalase , oxidative stress , mutant , mutagenesis , gene , microbiology and biotechnology , glutathione peroxidase , enzyme , botany , honey bees
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 H 2 O 2 , 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.