Cloning, purification and characterization of tehalose-6-phosphate synthase PoTPS1 and PoTPS5 from Paeonia ostii

Abstract

Abstract Trehalose-6-phosphate synthase (TPS) as a key enzyme in trehalose metabolism plays important roles in metabolic regulation and abiotic stress tolerance in many species. In our previous study, 10 TPS family members in Paeonia ostii have been identified, and among them PoTPS1 and PoTPS5 were regarded as critical genes in regulating growth and development of P. ostii. In this study, the full-length of cDNAs with 1698 nucleotides encoding PoTPS1 and 2571 nucleotides encoding PoTPS5 from P. ostii were cloned. The sequence analysis revealed that PoTPS1 protein belongs to the Class I group and PoTPS5 was a Class II TPS protein, and they possess highly conserved residues. The expression levels of PoTPS1 and PoTPS5 were induced by sugar and abiotic stress, especially under glucose and high temperature treatments. Then, PoTPS1 and PoTPS5 protein were expressed at high level in Escherichia coli and purified by affinity chromatography. The molecular mass of PoTPS1 and PoTPS5 recombinant proteins were about 116 kDa and 149 kDa respectively. The optimum temperature of PoTPS1 and PoTPS5 were 50 ℃ and 60 ℃, and the optimum pH for both PoTPS1 and PoTPS5 was 6.0. Metal cations such as Mg2+ and Zn2+ stimulated PoTPS1 activity significantly, and the Mg2+, Cu2+ and Zn2+ motivated PoTPS5 activity tremendously. The addition of chondroitin sulfate was shown to stimulate enzyme activity.