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Actin sequestering protein, profilin, regulates intracellular vesicle transport in Leishmania.
Molecular and Biochemical Parasitology ( IF 1.5 ) Pub Date : 2020-05-12 , DOI: 10.1016/j.molbiopara.2020.111280
Bindu Ambaru 1 , Anupriya Gopalsamy 2 , T V Satish Tammana 2 , Hosahalli S Subramanya 2 , Chhitar M Gupta 2
Affiliation  

Profilins are the key regulators of actin dynamics in all eukaryotic cells. However, little information is available on their biochemical properties and functions in kinetoplastids, such as Trypanosoma and Leishmania. We show here that Leishmania parasites express only one homolog of profilin (LdPfn), which catalyzes nucleotide exchange on G-actin and promotes actin polymerization at its low concentrations. However, at high concentrations, it strongly inhibits the polymerization process by sequestering actin monomers. We further demonstrate that LdPfn binds to actin in Leishmania promastigotes, by both immunofluorescence microscopy and IgG affinity chromatography. Further, we reveal that this protein besides binding to poly-null-proline motifs, also binds more efficiently to PI(3,5)P2, which is found on early or late endosomes or lysosomes, than to PI(4,5)P2 and PI(3,4,5)P3. Additionally, we show that heterozygous mutants of profilin display significantly slower growth and intracellular vesicle trafficking activity, which is reversed on episomal gene complementation. Together, these findings suggest that profilin regulates intracellular vesicle trafficking in Leishmania perhaps through its binding to polyphosphoinositides.



中文翻译:

肌动蛋白螯合蛋白,profilin,调节利什曼原虫中的细胞内囊泡运输。

脯氨酸蛋白是所有真核细胞中肌动蛋白动力学的关键调节剂。然而,关于它们在动植物体中的生化特性和功能的信息很少,例如锥虫利什曼原虫。我们在这里显示,利什曼原虫寄生虫只表达脯氨酸蛋白(LdPfn)的一个同系物,其催化G-肌动蛋白上的核苷酸交换并在其低浓度下促进肌动蛋白聚合。然而,在高浓度下,它通过螯合肌动蛋白单体强烈抑制聚合过程。我们进一步证明,LdPfn通过免疫荧光显微镜和IgG亲和层析与利什曼原虫前鞭毛体中的肌动蛋白结合。此外,我们发现该蛋白除了与聚脯氨酸基序还比PI(4,5)P2和PI(3,4,5)P3更有效地与早期或晚期内体或溶酶体上发现的PI(3,5)P2结合。此外,我们表明,profilin的杂合突变体显示出明显减慢的生长和细胞内囊泡运输活动,这在游离基因互补时被逆转。在一起,这些发现表明,profilin可能通过结合利多磷酸肌醇来调节利什曼原虫的细胞内小泡运输。

更新日期:2020-05-12
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