KINETOPLASTID RNA EDITING - COMPLEXES AND CATALYSTS

RNA editing in kinetoplastids involves post-transcriptional insertion and deletion of uridylates (Us) to produce mature mitochondrial mRNAs with sequences specified by trans acting small guide RNAs. In vitro st udies indicate the reaction pathway involves endonucleolytic cleavage of the precursor mRNA at the editing site, uridylate addition or remov al at the 3' end of the 5' cleavage product, followed by ligation to t he 3' cleavage product. This editing is catalyzed by a macromolecular complex that is in the early stages of characterization. Recent studie s have resolved the general mechanism of editing, and show that editin g occurs in association with a macromolecular complex.