Park H, Vettese M B, Fensom A H, Fisher K J, Aronson N N
Department of Molecular and Cell Biology, Althouse Laboratory, Pennsylvania State University, University Park 16802.
Biochem J. 1993 Mar 15;290 ( Pt 3)(Pt 3):735-41. doi: 10.1042/bj2900735.
Aspartylglycosaminuria (AGU) is a lysosomal storage disease principally occurring in Finland that results from mutations in the structural gene for glycosylasparaginase (AGU). This work characterizes the inheritance of two previously reported AGU mutations in a British patient [Ikonen, Aula, Grön, Tollersrud, Halila, Manninen, Syvänen and Peltonen (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 11222-11226]. Use of the PCR determined the glycosylasparaginase cDNA sequence from both parents of the British patient and his AGU-affected brother. The father of the British AGU-affected siblings was found to be a heterozygote carrier for a C-->T point mutation which causes an Ala-->Val amino-acid substitution, while the mother was heterozygous for a 7 bp deletion that results in premature translational termination. The brother of the previously studied patient was similarly shown to be a compound heterozygote. Expression in COS-1 cells revealed the paternal Ala-->Val amino-acid substitution destroyed glycosylasparaginase catalytic activity, prevented transport of the mutant protein to the lysosome, and prevented maturation of the enzyme precursor to its native subunit structure. The Ala-->Val mutation therefore affects glycosylasparaginase in a manner similar to the Finnish AGU Cys-->Ser substitution, further supporting a linkage of glycosylasparaginase catalytic activity to its lysosomal transport and subunit processing [Fisher and Aronson (1991) J. Biol. Chem. 266, 12105-12113]. In addition, a 5 bp deletion mutation from an American patient with AGU has been characterized. The deleted sequence occurs at the beginning of the glycosylasparaginase coding sequence, resulting in an extremely truncated polypeptide. The American 5 bp deletion and the British maternal 7 bp deletion possibly decrease mRNA stability.
天冬氨酰氨基葡糖苷酶缺乏症（AGU）是一种主要发生在芬兰的溶酶体贮积病，由天冬氨酰氨基葡糖苷酶（AGU）结构基因突变引起。本研究对一名英国患者中先前报道的两种AGU突变的遗传特征进行了分析[伊科宁、奥拉、格伦、托勒鲁德、哈利拉、曼尼宁、叙瓦内和佩尔顿宁（1991年）《美国国家科学院院刊》88，11222 - 11226]。通过聚合酶链反应（PCR）确定了该英国患者及其患AGU的兄弟的父母的天冬氨酰氨基葡糖苷酶cDNA序列。发现该患AGU的英国同胞的父亲是C→T点突变的杂合子携带者，该突变导致丙氨酸→缬氨酸氨基酸替换，而母亲是7 bp缺失的杂合子，这导致翻译提前终止。先前研究患者的兄弟同样被证明是复合杂合子。在COS - 1细胞中的表达显示，父亲的丙氨酸→缬氨酸氨基酸替换破坏了天冬氨酰氨基葡糖苷酶的催化活性，阻止了突变蛋白向溶酶体的转运，并阻止了酶前体成熟为其天然亚基结构。因此，丙氨酸→缬氨酸突变对天冬氨酰氨基葡糖苷酶的影响方式与芬兰AGU的半胱氨酸→丝氨酸替换相似，进一步支持了天冬氨酰氨基葡糖苷酶催化活性与其溶酶体转运和亚基加工之间的联系[费舍尔和阿隆森（1991年）《生物化学杂志》266，12105 - 12113]。此外，还对一名美国AGU患者的5 bp缺失突变进行了特征分析。缺失序列出现在天冬氨酰氨基葡糖苷酶编码序列的起始处，导致产生一个极度截短的多肽。美国的5 bp缺失和英国母亲的7 bp缺失可能会降低mRNA的稳定性。
