Thomae Bianca A, Rifki Oktay F, Theobald Michelle A, Eckloff Bruce W, Wieben Eric D, Weinshilboum Richard M
Department of Molecular Pharmacology & Experimental Therapeutics, Mayo Medical School-Mayo Clinic, Rochester, Minnesota 55905, USA.
J Neurochem. 2003 Nov;87(4):809-19. doi: 10.1046/j.1471-4159.2003.02027.x.
Sulfotransferase (SULT) 1A3 catalyzes the sulfate conjugation of catecholamines and structurally related drugs. As a step toward studies of the possible contribution of inherited variation in SULT1A3 to the pathophysiology of human disease and/or variation in response to drugs related to catecholamines, we have resequenced all seven coding exons, three upstream non-coding exons, exon-intron splice junctions and the 5'-flanking region of SULT1A3 using DNA samples from 60 African-American (AA) and 60 Caucasian-American (CA) subjects. Eight single nucleotide polymorphisms (SNPs) were observed in AA and five in CA subjects, including one non-synonymous cSNP (Lys234Asn) that was observed only in AA subjects with an allele frequency of 4.2%. This change in amino acid sequence resulted in only 28 +/- 4.5% (mean +/- SEM) of the enzyme activity of the wild-type (WT) sequence after transient expression in COS-1 cells, with a parallel decrease (54 +/- 2.2% of WT) in level of SULT1A3 immunoreactive protein. Substrate kinetic studies failed to show significant differences in apparent Km values of the two allozymes for either dopamine (10.5 versus 10.2 micro m for WT and variant, respectively) or the cosubstrate 3'-phosphoadenosine 5'-phosphosulfate (0.114 versus 0.122 micro m, respectively). The decrease in level of immunoreactive protein in response to this single change in amino acid sequence was due, at least in part, to accelerated SULT1A3 degradation through a proteasome-mediated process. These observations raise the possibility of ethnic-specific inherited alterations in catecholamine sulfation in humans.
磺基转移酶（SULT）1A3催化儿茶酚胺及结构相关药物的硫酸结合反应。为了研究SULT1A3遗传变异对人类疾病病理生理学和/或对儿茶酚胺相关药物反应差异可能产生的影响，我们使用60名非裔美国人（AA）和60名欧裔美国人（CA）受试者的DNA样本，对SULT1A3的全部7个编码外显子、3个上游非编码外显子、外显子 - 内含子剪接位点以及5'侧翼区域进行了重测序。在AA受试者中观察到8个单核苷酸多态性（SNP），在CA受试者中观察到5个，其中包括一个非同义cSNP（Lys234Asn），仅在AA受试者中出现，等位基因频率为4.2%。在COS - 1细胞中瞬时表达后，这种氨基酸序列的变化导致该酶活性仅为野生型（WT）序列的28±4.5%（平均值±标准误），同时SULT1A3免疫反应性蛋白水平也相应降低（为WT的54±2.2%）。底物动力学研究表明，两种同工酶对多巴胺（WT和变体分别为10.5 μM和10.2 μM）或共底物3'-磷酸腺苷5'-磷酸硫酸酯（分别为0.114 μM和0.122 μM）的表观Km值没有显著差异。这种氨基酸序列的单一变化导致免疫反应性蛋白水平下降，至少部分原因是通过蛋白酶体介导的过程加速了SULT1A3的降解。这些观察结果提示人类儿茶酚胺硫酸化存在种族特异性遗传改变的可能性。
