Molecular and Catalytic Properties of Glutathione Peroxidase Family Proteins from Pinus tabulaeformis

作者：Zhao, Li; Han, Xue-Min; Wang, Wei; Yang, Hai-Ling^*

来源：Plant Molecular Biology Reporter, 2014, 32(3): 771-778.

DOI：10.1007/s11105-013-0692-y

• Gene family
• Functional divergence
• Glutathione peroxidase
• Gene expression
• Enzymatic activity

Glutathione peroxidase (GPX) is one of the key enzymes that protect cells against oxidative damage caused by reactive oxygen species. Previous studies of plant GPXs focused mainly on angiosperms. In contrast, little information is available on the molecular characteristics of this gene family in gymnosperms. In this study, four GPX genes (PtaGPX1, 2, 3, and 4) were cloned from the gymnosperm Pinus tabulaeformis, which showed high protein sequence identity and similar expression patterns in various tissues. The four Pinus GPX proteins were expressed in Escherichia coli, and the purified proteins used thioredoxin, but not glutathione, as an electron donor. The four Pinus GPXs showed different enzymatic activities and kinetic characteristics, suggesting functional divergence. Two conserved Cys residues (corresponding to Cys44 and Cys92 of PtaGPX3) were identified in all plant GPXs, and their functions were assessed using site-directed mutagenesis. Cys44 and Cys92 of PtaGPX3 could form an intramolecular disulfide bond under oxidizing conditions. These two residues were critical components of active sites and contributed to catalytic activity. This study provides novel insights into the functional divergence and catalytic properties of the GPX family in gymnosperms.

• 出版日期2014-6
• 单位北京林业大学