Resistance to Bacillus thuringiensis toxin in Caenorhabditis elegans from loss of fucose
Resistance to Bacillus thuringiensis toxin in Caenorhabditis elegans from loss of fucose
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DOI：
10.1074/jbc.m606621200
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发表时间：
2007-02-02
影响因子：
4.8
通讯作者：
Aroian, Raffi V.
中科院分区：
文献类型：
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作者：
Barrows, Brad D.;Haslam, Stuart M.;Aroian, Raffi V.
在苏云金芽孢杆菌抗Cry5B晶体毒素突变株的筛选中，分离到秀丽隐杆线虫Bre-1基因突变。Bre-1突变动物与其他四个克隆的Bre突变动物的不同之处在于它们的抵抗力水平明显较低。在25℃的温度下，BRE-1动物的孵化仔数也显著减少。在这里，我们克隆了BRE-1基因，并对BRE-1突变表型进行了表征。BRE-1编码一种与GDP-甘露糖4，6-脱水酶有显著同源性的蛋白质，该酶催化GDP-甘露糖生物合成GDP-岩藻糖的第一步。向线虫肠道细胞注射GDP-岩藻糖而不是岩藻糖可以挽救bre-1突变表型。因此，线虫缺乏功能性岩藻糖回收途径。此外，我们证明bre-1突变动物在岩藻糖化糖脂的产生方面存在缺陷，并且bre-1突变动物使Cry5B糖脂受体的数量水平降低。最后，我们发现，BRE-1突变动物，虽然活着，但根据质谱学证据，显示缺乏岩藻糖化的N-和O-多糖。因此，线虫可以在没有岩藻糖的情况下存活，并且可以通过失去单糖生物合成途径来对晶体毒素产生抗性。
A mutation in the Caenorhabditis elegans bre-1 gene was isolated in a screen for Bacillus thuringiensis toxin-resistant (bre) mutants to the Cry5B crystal toxin made by B. thuringiensis. bre-1 mutant animals are different from the four other cloned bre mutants in that their level of resistance is noticeably lower. bre-1 animals also display a significantly reduced brood size at 25 C. Here we cloned the bre-1 gene and characterized the bre-1 mutant phenotype. bre-1 encodes a protein with significant homology to a GDP-mannose 4,6-dehydratase, which catalyzes the first step in the biosynthesis of GDP-fucose from GDP-mannose. Injection of GDP-fucose but not fucose into C. elegans intestinal cells rescues bre-1 mutant phenotypes. Thus, C. elegans lacks a functional fucose salvage pathway. Furthermore, we demonstrate that bre-1 mutant animals are defective in production of fucosylated glycolipids and that bre-1 mutant animals make quantitatively reduced levels of glycolipid receptors for Cry5B. We finally show that bre-1 mutant animals, although viable, show a lack of fucosylated N-and O-glycans, based on mass spectrometric evidence. Thus, C. elegans can survive with little fucose and can develop resistance to crystal toxin by loss of a monosaccharide biosynthetic pathway.