Molecular and enzymatic characterization of two enzymes BmPCD and BmDHPR involving in the regeneration pathway of tetrahydrobiopterin from the silkworm Bombyx mori
Molecular and enzymatic characterization of two enzymes BmPCD and BmDHPR involving in the regeneration pathway of tetrahydrobiopterin from the silkworm Bombyx mori
复制标题
参与家蚕四氢生物蝶呤再生途径的两种酶 BmPCD 和 BmDHPR 的分子和酶学表征
DOI：
10.1016/j.cbpb.2015.04.006
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发表时间：
2015-08-01
影响因子：
2.2
通讯作者：
Meng, Yan
中科院分区：
文献类型：
--
作者：
Li, Wentian;Gong, Meixia;Meng, Yan
四氢生物蝶呤(BH4)是芳香族氨基酸羟基酶和一氧化氮合酶的重要辅因子，在许多生物过程中起着关键作用。BH4缺乏与许多代谢综合征和神经心理障碍有关。哺乳动物体内的BH4浓度是通过从头合成途径和再生途径维持的。以往的研究表明，BH4的去新星途径在昆虫和哺乳动物中是相似的。然而，关于BH4(RPB)在昆虫中的再生途径的知识非常有限。家蚕中的几个突变体已被证实与BH4缺乏症有关，是研究昆虫RPB的良好模型。本研究从家蚕中克隆并鉴定了与RPB相关的两种酶的同源基因：蝶呤-4a-醇胺脱水酶(PCD)和二氢蝶呤还原酶(DHPR)。野生型家蚕幼虫脂肪体中存在DHPR的酶活性。结合转录谱结果表明，BmPcd和BmDhpr可能在家蚕的RPB中正常活动，BmDhpr在脑和性腺中的表达被激活，而BmPcd在BH4的从头途径缺乏柠檬时以更广泛的特殊模式表达。生化分析表明，重组BmDHPR在体外对NADH辅酶具有较高的酶活性和更合适的参数。本报告的结果提供了有关家蚕RPB的新信息，有助于更好地了解昆虫BH4的生物合成网络。(C)2015 Elsevier Inc.保留所有权利。
Tetrahydrobiopterin (BH4) is an essential cofactor of aromatic amino acid hydroxylases and nitric oxide synthase so that BH4 plays a key role in many biological processes. BH4 deficiency is associated with numerous metabolic syndromes and neuropsychological disorders. BH4 concentration in mammals is maintained through a de novo synthesis pathway and a regeneration pathway. Previous studies showed that the de nova pathway of BH4 is similar between insects and mammals. However, knowledge about the regeneration pathway of BH4 (RPB) is very limited in insects. Several mutants in the silkworm Bombyx mori have been approved to be associated with BH4 deficiency, which are good models to research on the RPB in insects. In this study, homologous genes encoding two enzymes, pterin-4a-carbinolamine dehydratase (PCD) and dihydropteridine reductase (DHPR) involving in RPB have been cloned and identified from B. mori. Enzymatic activity of DHPR was found in the fat body of wild type silkworm larvae. Together with the transcription profiles, it was indicated that BmPcd and BmDhpr might normally act in the RPB of B. mori and the expression of BmDhpr was activated in the brain and sexual glands while BmPcd was expressed in a wider special pattern when the de novo pathway of BH4 was lacked in lemon. Biochemical analyses showed that the recombinant BmDHPR exhibited high enzymatic activity and more suitable parameters to the coenzyme of NADH in vitro. The results in this report give new information about the RPB in B. mori and help in better understanding insect BH4 biosynthetic networks. (C) 2015 Elsevier Inc All rights reserved.