The Naegleria are ubiquitous free-living amoebae and are characterized by the presence of three phases in their biological cycle: trophozoite, cyst and flagellate. Of this genus, only Naegleria fowleri has been reported as pathogenic to humans. The proteasome is a multi-catalytic complex and is considered to be the most important structure responsible for the degradation of intracellular proteins. This structure is related to the maintenance of cellular homeostasis and, in pathogenic microorganisms, to the modulation of their virulence. Until now, the proteasome and its function have not been described for the Naegleria genus. In the current study, using bioinformatic analysis, protein sequences homologous to those reported for the subunits of the 20S proteasome in other organisms were found, and virtual modelling was used to determine their three-dimensional structure. The presence of structural and catalytic subunits of the 20S proteasome was detected by Western and dot blot assays. Its localization was observed by immunofluorescence microscopy to be mainly in the cytoplasm, and a leading role of the chymotrypsin-like catalytic activity was determined using fluorogenic peptidase assays and specific proteasome inhibitors. Finally, the role of the 20S proteasome in the proliferation and differentiation of Naegleria genus trophozoites was demonstrated.

在福氏耐格里是无处不在的自由生活的变形虫，并通过三个阶段在他们的生物循环存在的特点：滋养体，囊肿和鞭毛。在该属中，仅报道了家禽Naegleria fowleri对人类有致病性。蛋白酶体是一种多催化复合物，被认为是负责细胞内蛋白质降解的最重要结构。这种结构与细胞稳态的维持有关，在致病微生物中与它们的毒力调节有关。迄今为止，关于Naegleria的蛋白酶体及其功能尚未有描述属。在当前的研究中，使用生物信息学分析，发现了与其他生物中20S蛋白酶体亚单位报道的蛋白质序列同源的蛋白质序列，并使用虚拟模型确定了其三维结构。通过蛋白质印迹和斑点印迹分析检测到20S蛋白酶体的结构和催化亚基的存在。通过免疫荧光显微镜观察到其定位主要在细胞质中，并且使用荧光肽酶测定法和特定的蛋白酶体抑制剂确定了胰凝乳蛋白酶样催化活性的主导作用。最后，证明了20S蛋白酶体在Naegleria属滋养体的增殖和分化中的作用。