National Key Program of Microbiology and Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, 300071, China.
National Engineering Technology Research Center for Preservation of Agricultural Products, Key Laboratory of Storage of Agricultural Products, Ministry of Agriculture and Rural Affairs, Tianjin Key Laboratory of Postharvest Physiology and Storage of Agricultural Products, Tianjin, 300384, China.
Microbiol Res. 2020 Dec;241:126570. doi: 10.1016/j.micres.2020.126570. Epub 2020 Aug 9.
Invasive growth of yeast cells into nutrient agar is induced by different stresses and contributes to the survival of yeast cells under several adverse conditions. The mechanism of invasive growth of Saccharomyces cerevisiae has been extensively investigated. However, there is very little information about the mechanism of invasive growth of another human pathogen yeast Cryptococcus neoformans. Here, we report that deletion of a small and secreted cysteine-rich protein Cpl1 in C. neoformans JEC21 leads to increased adhesive and invasive growth into nutrient agar. The increased adhesive and invasive growth does not depend on the only known adhesion protein Cfl1 and its main controller Znf2. Cpl1Δ accumulates significantly higher level of intracellular labile zinc ion, leading to increased glucose uptake, higher level of mitochondrial membrane potential, ATP and Reactive Oxygen Species(ROS) production. Higher level of ROS activates Snf1, leading to invasive growth of Cpl1Δ. Three cysteine residues at the N-terminals of the cysteine-rich domain controls the increased invasive growth under nutrient sufficient conditions. This is the first report that a small and secreted cysteine-rich protein negatively regulates invasive growth of C. neoformans through regulating the intracellular labile zinc ion level. The function of this cysteine-rich domain was systematically investigated by site-directed mutagenensis in C. neoformans. The work contributes to understanding the function of this protein family and the invasive growth mechanism in C. neoformans.
酵母细胞侵入营养琼脂是由不同的应激诱导的，有助于酵母细胞在几种不利条件下存活。酿酒酵母的侵袭性生长机制已经得到了广泛的研究。然而，关于另一种人类病原体酵母新生隐球菌的侵袭性生长机制的信息却很少。在这里，我们报告称，在新生隐球菌 JEC21 中缺失一个小的、分泌型富含半胱氨酸的蛋白 Cpl1，会导致其在营养琼脂上的黏附和侵袭性生长增加。这种增加的黏附和侵袭性生长并不依赖于已知的唯一黏附蛋白 Cfl1 和其主要控制器 Znf2。Cpl1Δ 细胞内可利用的锌离子水平显著升高，导致葡萄糖摄取增加、线粒体膜电位、ATP 和活性氧（ROS）产生增加。较高水平的 ROS 激活 Snf1，导致 Cpl1Δ 的侵袭性生长。富含半胱氨酸结构域的 N 端的三个半胱氨酸残基控制着在营养充足条件下侵袭性生长的增加。这是首次报道一个小的、分泌型富含半胱氨酸的蛋白通过调节细胞内可利用的锌离子水平来负调控新生隐球菌的侵袭性生长。在新生隐球菌中，通过定点突变技术对这个富含半胱氨酸结构域的功能进行了系统研究。这项工作有助于理解这个蛋白家族的功能以及新生隐球菌的侵袭性生长机制。
