Chinese Bulletin of Botany ›› 2012, Vol. 47 ›› Issue (3): 248-256.DOI: 10.3724/SP.J.1259.2012.00248

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Molecular Characterization of Two Phi Glutathione S-transferases from Populus tomentosa

Di Li1, Zhenxin Tang1, Haijing Liu2, Qingyin Zeng2, Hailing Yang1*   

  1. 1College of Life Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China

    2State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
  • Received:2011-10-17 Revised:2012-02-17 Online:2012-05-01 Published:2012-07-06
  • Contact: Hailing Yang

Abstract: Plant glutathione S-transferases (GSTs) play important roles in stress tolerance and detoxification metabolism. We cloned two Phi GST genes (PtoGSTF1 and PtoGSTF2) from Populus tomentosa. PtoGSTF1 and PtoGSTF2 encode a protein of 215 and 218 amino acid residues, with a calculated molecular mass of 24.32 and 24.57 kDa, respectively. Genomic sequence analysis showed that PtoGSTF1 and PtoGSTF2 contained 2 introns. RT-PCR revealed PtoGSTF1 and PtoGSTF2 constitutively expressed in P. tomentosa. Recombinant PtoGSTF1 and PtoGSTF2 proteins were overexpressed in E. coli and purified by Ni-affinity chromatography. PtoGSTF1 and PtoGSTF2 showed enzymatic activities towards the substrates CDNB, NBD-Cl, NBC and Cum-OOH. The affinity to substrate NBD-Cl was 2.5-fold higher for PtoGSTF2 than PtoGSTF1, but the catalytic efficiency to NBD-Cl was 56.85-fold greater for PtoGSTF1 than PtoGSTF2. PtoGSTF1 showed greater thermal stability than PtoGSTF2. These results indicate the functional divergence between PtoGSTF1 and PtoGSTF2.