Chinese Bulletin of Botany ›› 2012, Vol. 47 ›› Issue (3): 248-256.DOI: 10.3724/SP.J.1259.2012.00248
Di Li1, Zhenxin Tang1, Haijing Liu2, Qingyin Zeng2, Hailing Yang1*
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.
Di Li, Zhenxin Tang, Haijing Liu, Qingyin Zeng, Hailing Yang. Molecular Characterization of Two Phi Glutathione S-transferases from Populus tomentosa[J]. Chinese Bulletin of Botany, 2012, 47(3): 248-256.
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