Differential Binding of Mitochondrial Transcripts by MRB8170 and MRB4160 Regulates Distinct Editing Fates of Mitochondrial mRNA in Trypanosomes.

Sameer Dixit,Julius Lukeš,Jernej Ule,Hassan Hashimi,Vojtěch David,Kathi Zarnack,Michaela Müller-Mcnicoll

doi:10.1128/mbio.02288-16

Sameer Dixit, Julius Lukeš + Show 5 more

Open Access

https://doi.org/10.1128/mbio.02288-16

Copy DOI

Abstract

ABSTRACTA dozen mRNAs are edited by multiple insertions and/or deletions of uridine residues in the mitochondrion of Trypanosoma brucei. Several protein complexes have been implicated in performing this type of RNA editing, including the mitochondrial RNA-binding complex 1 (MRB1). Two paralogous novel RNA-binding proteins, MRB8170 and MRB4160, are loosely associated with the core MRB1 complex. Their roles in RNA editing and effects on target mRNAs are so far not well understood. In this study, individual-nucleotide-resolution UV-cross-linking and affinity purification (iCLAP) revealed a preferential binding of both proteins to mitochondrial mRNAs, which was positively correlated with their extent of editing. Integrating additional in vivo and in vitro data, we propose that binding of MRB8170 and/or MRB4160 onto pre-mRNA marks it for the initiation of editing and that initial binding of both proteins may facilitate the recruitment of other components of the RNA editing/processing machinery to ensure efficient editing. Surprisingly, MRB8170 also binds never-edited mRNAs, suggesting that at least this paralog has an additional role outside RNA editing to shape the mitochondrial transcriptome.

Highlights

A dozen mRNAs are edited by multiple insertions and/or deletions of uridine residues in the mitochondrion of Trypanosoma brucei
IMPORTANCE Trypanosoma brucei mitochondrial mRNAs undergo maturation by RNA editing, a unique process involving decrypting open reading frames by the precise deletion and/or insertion of uridine (U) residues at specific positions on an mRNA. This process is catalyzed by multiprotein complexes, such as the RNA editing core complex, which provides the enzymatic activities needed for U insertion/deletion at a single editing site
We used the individual-nucleotide-resolution UV-cross-linking and affinity purification (iCLAP) protocol with the aim of identifying the direct RNA targets of the two accessory mitochondrial RNA-binding complex 1 (MRB1) subunits MRB8170 and MRB4160 in the mitochondrion of T. brucei (Fig. 1A)

Summary

Introduction

A dozen mRNAs are edited by multiple insertions and/or deletions of uridine residues in the mitochondrion of Trypanosoma brucei. IMPORTANCE Trypanosoma brucei mitochondrial mRNAs undergo maturation by RNA editing, a unique process involving decrypting open reading frames by the precise deletion and/or insertion of uridine (U) residues at specific positions on an mRNA. This process is catalyzed by multiprotein complexes, such as the RNA editing core complex, which provides the enzymatic activities needed for U insertion/deletion at a single editing site. We mapped at single-nucleotide resolution the RNA interactions of two unique RNA-binding proteins (RBPs) These RBPs are part of the mitochondrial RNA-binding complex 1, hypothesized to mediate multiple rounds of RNA editing. Little is known about how these individual transcripts, arising from a multicistronic precursor RNA, achieve distinct expression levels and how the abundance of these transcript categories is controlled in different life cycle stages of T. brucei [5, 10, 12]

Methods

Results

Conclusion