Department of Molecular Genetics, Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto , 160 College St., Toronto, M5S 3E1, Canada.
ACS Chem Biol. 2013 Dec 20;8(12):2785-93. doi: 10.1021/cb400607h. Epub 2013 Oct 16.
Candida albicans is an opportunistic pathogen capable of causing life-threatening infections in immunocompromised individuals. Despite its significant health impact, our understanding of C. albicans pathogenicity is limited, particularly at the molecular level. One of the largely understudied enzyme families in C. albicans are small molecule AdoMet-dependent methyltransferases (smMTases), which are important for maintenance of cellular homeostasis by clearing toxic chemicals, generating novel cellular intermediates, and regulating intra- and interspecies interactions. In this study, we demonstrated that C. albicans Crg1 (CaCrg1) is a bona fide smMTase that interacts with the toxin in vitro and in vivo. We report that CaCrg1 is important for virulence-related processes such as adhesion, hyphal elongation, and membrane trafficking. Biochemical and genetic analyses showed that CaCrg1 plays a role in the complex sphingolipid pathway: it binds to exogenous short-chain ceramides in vitro and interacts genetically with genes of glucosylceramide pathway, and the deletion of CaCRG1 leads to significant changes in the abundance of phytoceramides. Finally we found that this novel lipid-related smMTase is required for virulence in the waxmoth Galleria mellonella, a model of infection.
白色念珠菌是一种机会性病原体，能够在免疫功能低下的个体中引起危及生命的感染。尽管它对健康有重大影响，但我们对白色念珠菌致病性的了解有限，特别是在分子水平上。白色念珠菌中一个很大程度上研究不足的酶家族是小分子 AdoMet 依赖性甲基转移酶（smMTases），它们通过清除有毒化学物质、产生新的细胞中间产物以及调节种内和种间相互作用来维持细胞内稳态。在这项研究中，我们证明了白色念珠菌的 Crg1（CaCrg1）是一种真正的 smMTase，它可以与毒素在体外和体内相互作用。我们报告说，CaCrg1 对与毒力相关的过程很重要，如粘附、菌丝伸长和膜运输。生化和遗传分析表明，CaCrg1 在复杂的鞘脂代谢途径中发挥作用：它在体外与外源短链神经酰胺结合，并与葡糖脑苷脂途径的基因在遗传上相互作用，CaCRG1 的缺失导致植物神经酰胺的丰度发生显著变化。最后，我们发现这种新型与脂质相关的 smMTase 对于蜡蛾 Galleria mellonella 中的感染模型的毒力是必需的。
