Laboratório de Fungos de Importância Médica e Biotecnológica, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
Laboratório de Biologia Celular de Leveduras Patogênicas, Instituto de Microbiologia Paulo de Goés, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
mSphere. 2018 Apr 25;3(2). doi: 10.1128/mSphere.00023-18.
The yeast-like pathogen is an etiological agent of cryptococcosis. The major cryptococcal virulence factor is the polysaccharide capsule, which is composed of glucuronoxylomannan (GXM), galactoxylomannan (GalXM), and mannoproteins (MPs). The GXM and GalXM polysaccharides have been extensively characterized; however, there is little information about the role of mannoproteins in capsule assembly and their participation in yeast pathogenicity. The present study characterized the function of a predicted mannoprotein from , designated Krp1. Loss-of-function and gain-of-function mutants were generated, and phenotypes associated with the capsular architecture were evaluated. The null mutant cells were more sensitive to a cell wall stressor that disrupts beta-glucan synthesis. Also, these cells displayed increased GXM release to the culture supernatant than the wild-type strain did. The loss of Krp1 influenced cell-associated cryptococcal polysaccharide thickness and phagocytosis by J774.A1 macrophages in the early hours of interaction, but no difference in virulence in a murine model of cryptococcosis was observed. In addition, recombinant Krp1 was antigenic and differentially recognized by serum from an individual with cryptococcosis, but not with serum from an individual with candidiasis. Taken together, these results indicate that Krp1 is important for the cell wall structure, thereby influencing capsule assembly, but is not essential for virulence has the ability to escape from the host's immune system through poorly understood mechanisms and can lead to the death of healthy individuals. The role of mannoproteins in pathogenicity is not completely understood. The present work characterized a protein, Kpr1, that is essential for the maintenance of main virulence factor, the polysaccharide capsule. Our data contribute to the understanding of the role of Kpr1 in capsule structuring, mainly by modulating the distribution of glucans in cell wall.
酵母样病原体是隐球菌病的病因。主要的隐球菌毒力因子是多糖荚膜,它由葡聚糖(GXM)、半乳葡聚糖(GalXM)和甘露糖蛋白(MPs)组成。GXM 和 GalXM 多糖已得到广泛的描述;然而,关于甘露糖蛋白在荚膜组装中的作用及其在酵母致病性中的参与,信息很少。本研究对来自的一种预测的甘露糖蛋白 Krp1 进行了功能表征,命名为 Krp1。生成了功能丧失和功能获得突变体,并评估了与荚膜结构相关的表型。该缺失突变体细胞对破坏β-葡聚糖合成的细胞壁应激物更敏感。此外,与野生型菌株相比,这些细胞向培养上清液中释放更多的 GXM。Krp1 的缺失影响了细胞相关隐球菌多糖的厚度和 J774.A1 巨噬细胞的吞噬作用,但在隐球菌病的小鼠模型中没有观察到毒力的差异。此外,重组 Krp1 是抗原性的,并被隐球菌患者血清特异性识别,但不被念珠菌患者血清识别。综上所述,这些结果表明,Krp1 对细胞壁结构很重要,从而影响荚膜的组装,但对毒力不是必需的。该病原体能够通过尚未完全了解的机制逃避宿主的免疫系统,导致健康个体的死亡。甘露糖蛋白在中的致病性作用尚未完全阐明。本研究对一种蛋白 Kpr1 进行了表征,该蛋白对于维持的主要毒力因子,多糖荚膜,是必需的。我们的数据有助于理解 Kpr1 在荚膜结构中的作用,主要是通过调节葡聚糖在细胞中的分布。