The Role of the Trypanosoma cruzi TcNRBD1 Protein in Translation.

Camila Oliveira,Paulo Costa Carvalho,Lysangela Ronalte Alves,Samuel Goldenberg,Alexander F Palazzo

doi:10.1371/journal.pone.0164650

Abstract

The regulation of gene expression in trypanosomatids occurs mainly at the post-transcriptional level. Despite the importance of this type of control in Trypanosoma cruzi, few RNA binding proteins have been characterized. The RRM domain (RNA Recognition Motif) is one of the most abundant domains found in RNA-binding proteins in higher eukaryotes. Proteins containing the RRM domain are involved in the majority of post-transcriptional processes regulating gene expression. In this work, we aimed to characterize the protein TcNRBD1 from T. cruzi. TcNRBD1 is an RNA-binding protein that contains 2 RRM domains and is the ortholog of the P34 and P37 proteins from Trypanosoma brucei. The TcNRBD1 protein is expressed in all developmental stages of T. cruzi, and its localization pattern is concentrated at the perinuclear region. TcNRBD1 is associated with polysomes and with the 80S monosomes. Furthermore, sequencing of the mRNAs bound to TcNRBD1 allowed the identification of several transcripts that encode ribosomal proteins. Immunoprecipitation assays followed by mass spectrometry showed that the protein complexes with several ribosomal proteins from both the 40S and 60S subunits. In summary, the results indicate that TcNRBD1 is associated with different parts of the translation process, either by regulating mRNAs that encode ribosomal proteins or by acting in some step of ribosome assembly in T. cruzi.

Highlights

Chagas disease affects millions of people in America
The TcNRBD1 protein is closely related to p37 from T. brucei, another RNA-binding protein that was found to be essential for the ribosomal biogenesis and survival of the parasite
Using antibodies produced against the T. brucei P34/P37 proteins, the authors observed nuclear and nucleolar localizations for the protein and described a direct interaction with T. cruzi 5S rRNA but not with polyadenylated RNA

Summary

Introduction

Chagas disease affects millions of people in America. The causative agent is Trypanosoma cruzi, a flagellate protozoan parasite of the Kinetoplastida order. The life cycle of the parasite is very complex, with two different hosts and four distinct developmental forms [1]. The mechanisms that regulate the differentiation steps are not well understood [2]. There is no evidence for the regulation of transcription initiation for protein-coding genes in T. cruzi; the regulation of gene expression relies on post-transcriptional processes [3, 4]. The mature mRNAs are derived from the processing of polycistronic transcripts, and the distinct mRNAs are not functionally related, being produced at relatively constant levels the transcripts are present at different levels in the cytoplasm [5, 6]

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