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BioMed Research International
Volume 2014 (2014), Article ID 424767, 20 pages
http://dx.doi.org/10.1155/2014/424767
Research Article

α-Actinin TvACTN3 of Trichomonas vaginalis Is an RNA-Binding Protein That Could Participate in Its Posttranscriptional Iron Regulatory Mechanism

Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), 07360 México, DF, Mexico

Received 9 September 2013; Accepted 24 November 2013; Published 2 March 2014

Academic Editor: Wanderley De Souza

Copyright © 2014 Jaeson Santos Calla-Choque et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Trichomonas vaginalis is a sexually transmitted flagellated protist parasite responsible for trichomoniasis. This parasite is dependent on high levels of iron, favoring its growth and multiplication. Iron also differentially regulates some trichomonad virulence properties by unknown mechanisms. However, there is evidence to support the existence of gene regulatory mechanisms at the transcriptional and posttranscriptional levels that are mediated by iron concentration in T. vaginalis. Thus, the goal of this study was to identify an RNA-binding protein in T. vaginalis that interacts with the tvcp4 RNA stem-loop structure, which may participate in a posttranscriptional iron regulatory mechanism mediated by RNA-protein interactions. We performed RNA electrophoretic mobility shift assay (REMSA) and supershift, UV cross-linking, Northwestern blot, and western blot (WB) assays using cytoplasmic protein extracts from T. vaginalis with the tvcp4 RNA hairpin structure as a probe. We identified a 135-kDa protein isolated by the UV cross-linking assays as α-actinin 3 (TvACTN3) by MALDI-TOF-MS that was confirmed by LS-MS/MS and de novo sequencing. TvACTN3 is a cytoplasmic protein that specifically binds to hairpin RNA structures from trichomonads and humans when the parasites are grown under iron-depleted conditions. Thus, TvACTN3 could participate in the regulation of gene expression by iron in T. vaginalis through a parallel posttranscriptional mechanism similar to that of the IRE/IRP system.