UDP-glucose dehydrogenase plays multiple roles in the biology of the pathogenic fungus Cryptococcus neoformans
UDP-glucose dehydrogenase plays multiple roles in the biology of the pathogenic fungus Cryptococcus neoformans
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DOI：
10.1074/jbc.m408889200
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发表时间：
2004-12-03
影响因子：
4.8
通讯作者：
Doering, TL
中科院分区：
文献类型：
--
作者：
Griffith, CL;Klutts, JS;Doering, TL
新生隐球菌是一种被精心制作的多糖囊包围的致病真菌，对人类和其他哺乳动物的毒力是严格要求的。胶囊中近一半的糖残留物来自UDP-葡萄糖醛酸或其代谢物。为了研究这些核苷酸糖在新生芽孢杆菌中的作用，编码UDP-葡萄糖脱氢酶的基因被破坏。核苷酸糖库的质谱分析表明，突变株缺乏UDP-葡萄糖醛酸及其下游产物UDP-木糖，从而证实了敲除的效果，并表明没有使用替代途径来生产UDP-葡萄糖醛酸。突变体受到缺乏特定糖供体的显著影响，表现出细胞完整性、温度敏感性、在隐球菌病动物模型中缺乏生长以及形态缺陷。此外，在突变细胞上不能检测到多糖胶囊，尽管仍然有可能制造出缩写形式的胶囊成分，可能没有适当的表面显示。包膜缺陷在很大程度上与其他观察到的变化无关，因为由于其他基因突变而形成无囊化的细胞显示缺乏毒力，但在细胞完整性、温度敏感性或细胞形态方面没有变化。所有观察到的变化都通过纠正基因中断而逆转。
Cryptococcus neoformans is a pathogenic fungus surrounded by an elaborate polysaccharide capsule that is strictly required for its virulence in humans and other mammals. Nearly half of the sugar residues in the capsule are derived from UDP-glucuronic acid or its metabolites. To examine the role of these nucleotide sugars in C. neoformans, the gene encoding UDP-glucose dehydrogenase was disrupted. Mass spectrometry analysis of nucleotide sugar pools showed that the resulting mutant lacked both UDP-glucuronic acid and its downstream product, UDP-xylose, thus confirming the effect of the knockout and indicating that an alternate pathway for UDP-glucuronic acid production was not used. The mutant was dramatically affected by the lack of specific sugar donors, demonstrating altered cell integrity, temperature sensitivity, lack of growth in an animal model of cryptococcosis, and morphological defects. Additionally, the polysaccharide capsule could not be detected on the mutant cells, although the possibility remains that abbreviated forms of capsule components are made, possibly without proper surface display. The capsule defect is largely independent of the other observed changes, as cells that are acapsular because of mutations in other genes show lack of virulence but do not exhibit alterations in cell integrity, temperature sensitivity, or cellular morphology. All of the observed alterations were reversed by correction of the gene disruption.