Trypanosoma brucei RNA Editing Complex: Band II is Structurally Critical and Maintains Band V Ligase, Which is Nonessential

Sean F. O'Hearn, Catherine E. Huang, Mike Hemann, Alevtina Zhelonkina, Barbara Sollner-Webb

Research output: Contribution to journalArticlepeer-review


Maturation of Trypanosoma brucei mitochondrial mRNA involves massive posttranscriptional insertion and deletion of uridine residues. This RNA editing utilizes an enzymatic complex with seven major proteins, band I through band VII. We here use RNA interference (RNAi) to examine the band II and band V proteins. Band II is found essential for viability; it is needed to maintain the normal structure of the editing complex and to retain the band V ligase protein. Previously, band III was found essential for certain activities, including maintenance of the editing complex and retention of the band IV ligase protein. Thus, band II and band V form a protein pair with features analogous to the band III/band IV ligase pair. Since band V is specific for U insertion and since band IV is needed for U deletion, their parallel organization suggests that the editing complex has a pseudosymmetry. However, unlike the essential band IV ligase, RNAi to band V has only a morphological but no growth rate effect, suggesting that it is stimulatory but nonessential. Indeed, in vitro analysis of band V RNAi cell extract demonstrates that band IV can seal U insertion when band V is lacking. Thus, band IV ligase is the first activity of the basic editing complex shown able to serve in both forms of editing. Our studies also indicate that the U insertional portion may be less central in the editing complex than the corresponding U deletional portion.

Original languageEnglish (US)
Pages (from-to)7909-7919
Number of pages11
JournalMolecular and cellular biology
Issue number21
StatePublished - Nov 2003

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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