Varin L, DeLuca V, Ibrahim R K, Brisson N
Département de Biochimie, Université de Montréal, Québec, Canada.
Proc Natl Acad Sci U S A. 1992 Feb 15;89(4):1286-90. doi: 10.1073/pnas.89.4.1286.
cDNA clones coding for flavonol 3- and 4'-sulfotransferases (STs) were isolated by antibody screening of a cDNA expression library produced from poly(A)+ RNA extracted from terminal buds of Flaveria chloraefolia. Sequence analysis revealed full-length cDNA clones with open reading frames of 933 and 960 base pairs, which encode polypeptides containing 311 and 320 amino acids, respectively. This corresponds to a molecular mass of 36,442 Da for the 3-ST and 37,212 Da for the 4'-ST. Expression of these clones in Escherichia coli led to the synthesis of beta-galactosidase-ST fusion proteins having the same substrate and position specificities as those for the 3- and 4'-flavonol ST enzymes isolated from the plant. Comparison of the deduced amino acid sequence of the two clones revealed an overall identity of 69% in 311 amino acid residues. The two flavonol STs of F. chloraefolia also shared significant sequence similarities with steroid and aryl STs found in animal tissues and with the senescence marker protein 2 isolated from rat liver, suggesting an evolutionary link between plant and animal STs.
通过对从绿黄菊（Flaveria chloraefolia）顶芽提取的聚腺苷酸加尾RNA（poly(A)+ RNA）构建的cDNA表达文库进行抗体筛选，分离出了编码黄酮醇3 - 和4'-磺基转移酶（STs）的cDNA克隆。序列分析揭示了全长cDNA克隆，其开放阅读框分别为933和960个碱基对，分别编码含有311和320个氨基酸的多肽。这对应于3 - ST的分子量为36,442 Da，4'-ST的分子量为37,212 Da。这些克隆在大肠杆菌中的表达导致合成了β-半乳糖苷酶-ST融合蛋白，其具有与从该植物中分离出的3 - 和4'-黄酮醇ST酶相同的底物和位置特异性。对这两个克隆推导的氨基酸序列进行比较，发现在311个氨基酸残基中总体一致性为69%。绿黄菊的两种黄酮醇STs还与动物组织中发现的类固醇和芳基STs以及从大鼠肝脏分离出的衰老标记蛋白2具有显著的序列相似性，表明植物和动物STs之间存在进化联系。
