Soto-Castro Liliana, Plata-Guzmán Laura Yuliana, Figueroa-Angulo Elisa Elvira, Calla-Choque Jaeson Santos, Reyes-López Magda, de la Garza Mireya, León-Sicairos Nidia, Garzón-Tiznado José Antonio, Arroyo Rossana, León-Sicairos Claudia
Programa Regional del Noroeste para el Posgrado en Biotecnología de la Facultad de Ciencias Químico Biológicas, Universidad Autónoma de Sinaloa, Av. de las Américas y Josefa Ortíz (Cd. Universitaria) Culiacán, Sinaloa 80030, Mexico.
Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Avenida Instituto Politécnico Nacional No. 2508, Colonia San Pedro Zacatenco, México, D.F. 07360, Mexico.
Microbiology (Reading). 2017 Sep;163(9):1329-1342. doi: 10.1099/mic.0.000431. Epub 2017 Sep 4.
In Entamoeba histolytica, iron modulates virulence and gene expression via unknown regulatory mechanisms. The existence of a posttranscriptional iron regulatory system parallel with the iron-responsive element (IRE)/iron regulatory protein (IRP) system in the protozoan Trichomonas vaginalis has recently been reported. Due to their evolutionary closeness and the importance of iron for growth and virulence in these protozoa, we hypothesized the existence of an IRE/IRP-like mechanism in E. histolytica. To determine the presence of IRE-like elements in some mRNAs from this parasite, we performed in silico analyses of the 5'- and 3'-UTRs of mRNAs encoding virulence factors and cytoskeleton, ribosomal and metabolism proteins. The Zuker mfold software predicted IRE-like secondary structures in 52 of the 135 mRNAs analysed. However, only nine structures shared sequence similarity with the apical loop sequence (CAGUGN) of the previously reported human IRE-ferritin, whereas the GUU/UUG protozoan-specific motif was detected in 23 stem-loop structures. A new motif, AUU/AUUU, was also observed in 23 structures, suggesting the possible existence of an amoeba-specific motif. Additionally, cross-linking and RNA electrophoretic mobility shift assays showed specific RNA-protein interactions, using as a model two amoebic IRE-like elements from iron-regulated mRNAs and HeLa, T. vaginalis and E. histolytica cytoplasmic proteins. Our data suggest the presence of a posttranscriptional iron regulatory IRE/IRP-like mechanism in E. histolytica.
在溶组织内阿米巴中，铁通过未知的调控机制调节毒力和基因表达。最近有报道称，原生动物阴道毛滴虫中存在一种与铁反应元件（IRE）/铁调节蛋白（IRP）系统平行的转录后铁调节系统。鉴于它们在进化上的亲缘关系以及铁对这些原生动物生长和毒力的重要性，我们推测溶组织内阿米巴中存在IRE/IRP样机制。为了确定该寄生虫某些mRNA中是否存在类似IRE的元件，我们对编码毒力因子、细胞骨架、核糖体和代谢蛋白的mRNA的5'和3'非翻译区进行了计算机分析。Zuker mfold软件在分析的135个mRNA中的52个中预测到了类似IRE的二级结构。然而，只有9个结构与先前报道的人类IRE-铁蛋白的顶端环序列（CAGUGN）具有序列相似性，而在23个茎环结构中检测到了GUU/UUG原生动物特异性基序。在23个结构中还观察到一个新的基序AUU/AUUU，这表明可能存在阿米巴特异性基序。此外，交联和RNA电泳迁移率变动分析显示了特定的RNA-蛋白质相互作用，使用来自铁调节mRNA的两个阿米巴样IRE元件以及HeLa、阴道毛滴虫和溶组织内阿米巴的细胞质蛋白作为模型。我们的数据表明溶组织内阿米巴中存在转录后铁调节IRE/IRP样机制。
