Crystal Structures of T. brucei MRP1/MRP2 Guide-RNA Binding Complex Reveal RNA Matchmaking Mechanism

Maria A. Schumacher, Elham Karamooz, Alena Zíková, Lukáš Trantírek, Julius Lukeš

Research output: Contribution to journalArticlepeer-review

89 Scopus citations

Abstract

The mitochondrial RNA binding proteins MRP1 and MRP2 form a heteromeric complex that functions in kinetoplastid RNA editing. In this process, MRP1/MRP2 serves as a matchmaker by binding to guide RNAs and facilitating their hybridization with cognate preedited mRNAs. To understand the mechanism by which this complex performs RNA matchmaking, we determined structures of Trypanosoma brucei apoMRP1/MRP2 and an MRP1/MRP2-gRNA complex. The structures show that MRP1/MRP2 is a heterotetramer and, despite little sequence homology, each MRP subunit exhibits the same "Whirly" transcription-factor fold. The gRNA molecule binds to the highly basic β sheet surface of the MRP complex via nonspecific, electrostatic contacts. Strikingly, while the gRNA stem/loop II base is anchored to the basic surface, stem/loop I (the anchor sequence) is unfolded and its bases exposed to solvent. Thus, MRP1/MRP2 acts as an RNA matchmaker by stabilizing the RNA molecule in an unfolded conformation suitable for RNA-RNA hybridization.

Original languageEnglish (US)
Pages (from-to)701-711
Number of pages11
JournalCell
Volume126
Issue number4
DOIs
StatePublished - Aug 25 2006
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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