Cloning And Bioinformatics Analysis Of GST Genes From Porphyra Yezoensis

Glutathione s-transferase (GSTs) is a family of multifunctional isozyme distributed widelyin animals, plants, microorganisms. It mainly catalyzes the combination of Glutathione inorganisms with exogenous toxic and oxidized compounds to function as antioxidant andantitoxic, thus to protect organisms from damage. Porphyra yezoensis belongs to the largealgae lives in the intertidal zone. It is one of the most important economic seaweed cultured inChina. The researches on gene cloning, genetic variation and mechanism of resistance aresignificant.The research on GST gene could help us to deeply understand the mechanism ofantitoxic and resistance in algae, and lay a foundation for further understanding the details ofmolecular mechanism of adaptation of algae and other organisms.In this experiment,63ESTs of GST from P. yezoensis were searched in the DNAdatabase of KDRI, and three contigs with full ORF sequence of GST gene were obtained afteralignment. One of the three contigs were named PyGST which was no any match in the NCBIdatabase. According to the DNA sequence of P. yezoensis, a pair of specific primer weredesigned and ORF of PyGST gene were amplified by using the3’RACE-PCR technique.This ORF sequence of PyGST gene has a length of915bp. The sequence of the ORF anddeduced amino acid sequence were used in the bioinformatics analysis and the construction ofthe phylogenetic tree. Bioinformatics analysis includes the analysis of physical and chemicalproperty, hydrophobicity, phosphorylation site and functional domain; prediction of crossingmembrane structure, signal peptide, secondary and tertiary structure; subcellular localizationof the amino acid sequence and construction of phylogenetic tree.The results showed that PyGST had not across membrane domains，and no signalpeptide sequence, which implied that it might locate in cytoplasm, so PyGST is a cytoplasmicGST. The analysis results of domain structure showed that the PyGST sequence structure issimilar with that of other P. yezoensis GSTs with domains including GST_C and GST_N. TheGST proteins from P. yezoensis might have very similar functions because of their highlyconservative and spatial similarity in the tertiary structure. The comparison results ofphylogenetic tree indicated that plants GST genes composed a complex family and the resultswas in accordance with the traditional taxonomy of organisms. The selected sixty-one speciesincluding fungi, algae, lichen, moss, fern, and seed plants were clustered obviously. Theseresults provides valuable theoretical basis for the further study of the GST gene and poisonresistance molecular mechanism research of P. yezoensis.