Molecular characterization of a phospholipid-hydroperoxide glutathione peroxidase from the bumblebee Bombus ignitus.
Phospholipid-hydroperoxide glutathione peroxidase (PHGPx or GPx4; EC 1.11.1.12) is an antioxidant enzyme that reduces lipid hydroperoxides in biomembranes. Here, we cloned and characterized cys-PHGPx from the bumblebee Bombus ignitus (Bi-PHGPx). The Bi-PHGPx gene consists of 4 exons, encoding 168 amino acid residues with a canonical cys-codon at residue 45 and active site residues Gln(82) and Trp(134). Recombinant Bi-PHGPx, expressed as a 19 kDa protein in baculovirus-infected insect cells, exhibited enzymatic activity against PLPC-OOH and H(2)O(2) using glutathione as an electron donor. Tissue distribution analyses showed the presence of Bi-PHGPx in all tissues examined. Bi-PHGPx transcripts were upregulated by stresses, such as wounding, H(2)O(2) exposure, external temperature shock, and starvation. Under H(2)O(2) overload, the RNA interference (RNAi)-induced thioredoxin peroxidase (BiTPx1)-knock-down B. ignitus worker bees showed upregulated expression of Bi-PHGPx in the fat body. These results indicate that Bi-PHGPx is a stress-inducible antioxidant enzyme that acts on phospholipid hydroperoxide and H(2)O(2).
Hu
Zhigang
Z
College of Natural Resources and Life Science, Dong-A University, Busan 604-714, Republic of Korea.
Lee
Kwang Sik
KS
Choo
Young Moo
YM
Yoon
Hyung Joo
HJ
Kim
Iksoo
I
Wei
Ya Dong
YD
Gui
Zhong Zheng
ZZ
Zhang
Guo Zheng
GZ
Sohn
Hung Dae
HD
Jin
Byung Rae
BR
D000595:Amino Acid Sequence; D000818:Animals; D001516:Bees / Q000201:enzymology / Q000235:genetics*; D015152:Blotting, Northern; D015153:Blotting, Western; D002460:Cell Line; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D005979:Glutathione Peroxidase / Q000235:genetics* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D018411:Spodoptera; D013696:Temperature
D019476:Insect Proteins; D011994:Recombinant Proteins; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D005979:Glutathione Peroxidase