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Molecular Mechanism of Cell Cycle Regulation of Pathogenic Fungi Cryptococcus neoformans

病原真菌新型隐球菌细胞周期调控的分子机制

基本信息

批准号：
17590386
负责人：
KAWAMOTO Susumu
金额：
$ 2.37万
依托单位：
Chiba University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17590386/
关键词：
Fungi Infectious disease Cell cycle Gene Protein Cryptococcus Cyclin Cyclin-dependent kinase

项目摘要

Cryptococcus neoformans is an opportunistic pathogen, belongs to basidiomycetous fungus, and has unique properties in cell cycle progression. In standard liquid condition, doubling time of exponentially growing C. neoformans was 132+-16 min, and duration time of G1, S, G2, and M phases were found to be about 71, 18, 25, and 18 min, respectively. DNA synthesis started before bud emergence, and completed by the stage that the size of bud became 1/4 of the mother cell. The doubling time of daughter cells was about twice as that of the mother cells. The spindle pole body was located on the outer nuclear envelop and showed duplicated form in G1 to G2 phase. Cyclin-dependent kinase (Ddk) has been known to control cell cycle by changing conformation and biological functions. Cdk has been also known to bind to or separate from the molecules, expecially cyclins, and to change substrate specificity of the enzyme. In C.neoformans, Cdk and cyclins were cloned by ourselves, and protein-protein interaction profile between the two proteins were analyzed and constructed in silico. We are further analyzing structure-function relationship between C. neoformans Cdk and cyclins.C. neoformans is killed by the bacterium Staphylococcus aureus and this death is inhibited by soluble capsular polysaccharides. To investigate the mechanism of killing, cells in co-culture were examined under scanning and transmission electron microscopy. S. aureus attached to the capsule of C. neoformans, and the ultrastructure of the attached C. neoformans cells was characteristic of dead cells. We identified the molecules that contributed to the fungal-bacterial interaction : triosephosphate isomerase (TPI) on S. aureus adheres to the capsule of C. neoformans by recognizing the structure of mannotriose units in the backbone of GXM ; we suggest that this contact is required for killing of C. neoformans.

新型隐球菌是一种条件致病菌，属于担子菌属真菌，在细胞周期进程中具有独特的性质。在标准液条件下，指数生长的新生小蠊的倍增时间为132+-16 min， G1、S、G2和M相的持续时间分别为71、18、25和18 min。DNA合成开始于芽出生前，到芽大小为母细胞的1/4时完成。子细胞的倍增时间大约是母细胞的两倍。纺锤极体位于外核膜上，G1期至G2期呈重复形态。周期蛋白依赖性激酶（Ddk）通过改变构象和生物学功能来控制细胞周期。Cdk也被认为与分子结合或分离，特别是细胞周期蛋白，并改变酶的底物特异性。在C.neoformans中，我们克隆了Cdk蛋白和细胞周期蛋白，分析并构建了两者之间的蛋白相互作用谱。我们进一步分析了C. neoformans Cdk和cyclins.C的结构-功能关系。neoformans被金黄色葡萄球菌杀死，这种死亡被可溶性荚膜多糖抑制。在扫描电镜和透射电镜下观察了共培养细胞的杀伤机制。金黄色葡萄球菌附着在新生葡萄球菌的荚膜上，附着的新生葡萄球菌细胞超微结构呈死细胞特征。我们确定了促成真菌-细菌相互作用的分子：金黄色葡萄球菌上的三磷酸异异构酶（TPI）通过识别GXM主干中的甘露糖单元的结构附着在新生葡萄球菌的荚膜上；我们认为这种接触是杀死新生梭状虫所必需的。