title: Iron responsive-like elements in the parasite Entamoeba histolytica.
abstract: 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.
authors.affiliation: 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.
authors.forename: Liliana
authors.initials: L
authors.lastname: Soto-Castro
authors.affiliation: 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.
authors.forename: Laura Yuliana
authors.initials: LY
authors.lastname: Plata-Guzmán
authors.affiliation: 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.
authors.forename: Elisa Elvira
authors.initials: EE
authors.lastname: Figueroa-Angulo
authors.affiliation: 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.
authors.forename: Jaeson Santos
authors.initials: JS
authors.lastname: Calla-Choque
authors.affiliation: Departamento de Biología Celular, 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.
authors.forename: Magda
authors.initials: M
authors.lastname: Reyes-López
authors.affiliation: Departamento de Biología Celular, 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.
authors.forename: Mireya
authors.initials: M
authors.lastname: de la Garza
authors.affiliation: 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.
authors.forename: Nidia
authors.initials: N
authors.lastname: León-Sicairos
authors.affiliation: 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.
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Garzón-Tiznado
authors.affiliation: 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.
authors.forename: Rossana
authors.initials: R
authors.lastname: Arroyo
authors.affiliation: 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.
authors.forename: Claudia
authors.initials: C
authors.lastname: León-Sicairos
mesh_terms: D002478:Cells, Cultured; D004748:Entamoeba histolytica / Q000235:genetics* / Q000378:metabolism*; D004749:Entamoebiasis / Q000378:metabolism / Q000469:parasitology; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006790:Host-Parasite Interactions; D006801:Humans; D055029:Inverted Repeat Sequences; D007501:Iron / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D020218:Response Elements
chemical_list: D012333:RNA, Messenger; D007501:Iron