Virulence and functions of myosin II are inhibited by overexpression of light meromyosin in Entamoeba histolytica
Virulence and functions of myosin II are inhibited by overexpression of light meromyosin in Entamoeba histolytica
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DOI：
10.1091/mbc.9.6.1537
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发表时间：
1998-06-01
影响因子：
3.3
通讯作者：
Guillén, N
中科院分区：
文献类型：
--
作者：
Arhets, P;Olivo, JC;Guillén, N
在溶解组织内阿米巴表面受体的封端过程中，细胞形态发生了一些变化。阿米巴虫发育出尿突，这是一种由膜内陷形成的附属物，它积累了覆盖过程中产生的配体-受体复合体。膜脱落在尿液区域特别活跃，并导致累积的配体被清除。这种附属物被认为参与了针对宿主免疫反应的寄生防御机制，因为它消除了与阿米巴表面结合的补体和特定抗体。实验表明，影响肌球蛋白II重链磷酸化的药物阻止了肌球蛋白II的这种活性，这表明肌球蛋白II参与了表面受体的封顶过程。为了了解这种机械酶在表面受体封顶中的作用，构建了一株肌球蛋白II显性负性菌株。该突变体是第一个通过基因工程获得的细胞骨架缺陷菌株。它是通过过度表达肌球蛋白轻质结构域而获得的，该结构域是肌球蛋白II细丝形成所必需的。过表达肌球蛋白轻区的溶组织型大肠杆菌表现为肌球蛋白II缺失表型，表现为运动异常、不能形成尿液和刀豆球蛋白A处理后不能完成封盖过程。此外，转染体对人结肠细胞的阿米巴细胞毒力显著降低，表明细胞骨架在寄生虫致病中起作用。
Several changes in cell morphology take place during the capping of surface receptors in Entamoeba histolytica. The amoebae develop the uroid, an appendage formed by membrane invaginations, which accumulates ligand-receptor complexes resulting from the capping process. Membrane shedding is particularly active in the uroid region and leads to the elimination of accumulated ligands. This appendage has been postulated to participate in parasitic defense mechanisms against the host immune response, because it eliminates complement and specific antibodies bound to the amoeba surface. The involvement of myosin II in the capping process of surface receptors has been suggested by experiments showing that drugs that affect myosin II heavy-chain phosphorylation prevent this activity. To understand the role of this mechanoenzyme in surface receptor capping, a myosin II dominant negative strain was constructed. This mutant is the first genetically engineered cytoskeleton-deficient strain of E. histolytica. It was obtained by overexpressing the light meromyosin domain, which is essential for myosin II filament formation. E. histolytica overexpressing light meromyosin domain displayed a myosin II null phenotype characterized by abnormal movement, failure to form the uroid, and failure to undergo the capping process after treatment with concanavalin A. In addition, the amoebic cytotoxic capacities of the transfectants on human colon cells was dramatically reduced, indicating a role for cytoskeleton in parasite pathogenicity.