Reconstitution of uridine-deletion precleaved RNA editing with two recombinant enzymes

AUTOR(ES)
FONTE

National Academy of Sciences

RESUMO

Uridine insertion/deletion RNA editing in trypanosomatid mitochondria is a posttranscriptional RNA modification phenomenon required for translation of mitochondrial mRNAs. This process involves guide RNA-mediated cleavage at a specific site, insertion or deletion of Us from the 3′ end of the 5′ mRNA fragment, and ligation of the two mRNA fragments. The Leishmania major RNA ligase-containing complex protein 2 expressed in insect cells has a 3′–5′ exoribonuclease activity and was therefore renamed RNA editing exonuclease 1 (REX1). Recombinant REX1 specifically trims 3′ overhanging Us and stops at a duplex region. Evidence is presented that REX1 is responsible for deletion of the 3′ overhanging Us from the bridged mRNA 5′ cleavage fragment and that RNA editing ligase 1 is responsible for the ligation of the two mRNA cleavage fragments in U-deletion editing. The evidence involves both in vivo down-regulation of REX1 expression in Trypanosoma brucei by RNA interference and the reconstitution of precleaved U-deletion in vitro editing with only two recombinant enzymes: recombinant REX1 and recombinant RNA editing ligase 1.

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