Hongoh Y, Sasaki T, Ishikawa H
Department of Biological Sciences, Graduate School of Science, University of Tokyo, Japan.
Insect Biochem Mol Biol. 2000 Feb;30(2):173-82. doi: 10.1016/s0965-1748(99)00116-2.
A urate oxidase (uricase; EC 1.7.3.3) gene of the yeast-like fungal endosymbiont of the brown planthopper, Nilaparvata lugens, was cloned, and sequenced together with its flanking regions. The gene comprised a open reading frame of 987 bp, that was split into two parts by a single 96 bp intron. The encoded uricase was 296 amino acids with 62% sequence identity with that of Aspergillus flavus. The molecular weight deduced was 32,882, and the predicted isoelectric point was 6.06. The symbiont's uricase conserved all the known consensus motifs, except the C-terminal PTS-1, Ser-basic-Leu. The leucine at the third position of PTS-1 was replaced by serine in the C-terminus of the symbiont's uricase. The symbiont's uricase gene was successfully expressed in Escherichia coli, and the product, tagged with histidine residues, was purified. The symbiont's uricase, thus produced, was as active as those from plants and animals, but less active than those from other fungi.
克隆了褐飞虱（Nilaparvata lugens）酵母样真菌内共生菌的尿酸氧化酶（尿酸酶；EC 1.7.3.3）基因，并对其及其侧翼区域进行了测序。该基因包含一个987 bp的开放阅读框，被一个96 bp的单一内含子分成两部分。编码的尿酸酶有296个氨基酸，与黄曲霉的尿酸酶序列同一性为62%。推导的分子量为32,882，预测的等电点为6.06。共生菌的尿酸酶保留了所有已知的共有基序，但C端的PTS-1（Ser-basic-Leu）除外。PTS-1第三位的亮氨酸在共生菌尿酸酶的C端被丝氨酸取代。共生菌的尿酸酶基因在大肠杆菌中成功表达，带有组氨酸残基标签的产物被纯化。由此产生的共生菌尿酸酶与来自植物和动物的尿酸酶活性相当，但比来自其他真菌的尿酸酶活性低。
