文献类型： 外文期刊

作者： Nong, Han ¹ ; Zhang, Jia-Ming ¹ ; Li, Ding-Qin ² ; Wang, Meng ² ; Sun, Xue-Piao ² ; Zhu, Yun Judy ² ; Meijer, Johan ⁵ ; W ¹ ;

作者机构： 1.Chinese Acad Trop Agr Sci, Spice & Beverage Crops Res Inst, Natl Ctr Trop Crops Engn & Technol Res, Wannin 571533, Peoples R China

2.CATAS, Inst Trop Biosci & Biotechnol, MOA Key Biotechnol Lab Trop Crops, Haikou 571101, Peoples R China

3.Hainan Univ, Coll Agr, Haikou 571101, Peoples R China

4.Yunnan Acad Agr Sci, Inst Biotechnol, Kunming 650205, Peoples R China

5.Swedish Univ Agr Sci, Bioctr, Dept Plant Biol & Forest Genet, SE-75007 Uppsala, Sw

期刊名称：JOURNAL OF INTEGRATIVE PLANT BIOLOGY （ 影响因子：7.061； 五年影响因子：6.002 ）

ISSN： 1672-9072

年卷期： 2010 年 52 卷 10 期

页码：

收录情况： SCI

摘要： Plant thioglucosidases are the only known S-glycosidases in the large superfamily of glycosidases. These enzymes evolved more recently and are distributed mainly in Brassicales. Thioglucosidase research has focused mainly on the cruciferous crops due to their economic importance and cancer preventive benefits. In this study, we cloned a novel myrosinase gene, CpTGG1, from Carica papaya Linnaeus. and showed that it was expressed in the aboveground tissues in planta. The recombinant CpTGG1 expressed in Pichia pastoris catalyzed the hydrolysis of both sinigrin and glucotropaeolin (the only thioglucoside present in papaya), showing that CpTGG1 was indeed a functional myrosinase gene. Sequence alignment analysis indicated that CpTGG1 contained all the motifs conserved in functional myrosinases from crucifers, except for two aglycon-binding motifs, suggesting substrate priority variation of the non-cruciferous myrosinases. Using sinigrin as substrate, the apparent K-m and V-max values of recombinant CpTGG1 were 2.82 mM and 59.9 mu mol min-1 mg protein-1, respectively. The K-cat/K-m value was 23 s-1 mM-1. O-beta-glucosidase activity towards a variety of substrates were tested, CpTGG1 displayed substrate-dependent and ascorbic acid-independent O-beta-glucosidase activity towards 2-nitrophenyl-beta-D-glucopyranoside and 4-nitrophenyl-beta-D-glucopyranoside, but was inactive towards glucovanillin and n-octyl-beta-D-glucopyranoside. Phylogenetic analysis indicated CpTGG1 belongs to the MYR II subfamily of myrosinases.