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Science. 2005 Sep 2;309(5740):1584-7.

An mRNA is capped by a 2', 5' lariat catalyzed by a group I-like ribozyme.

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  • 1Department of Medical Biochemistry and Genetics, Panum Institute, University of Copenhagen, DK-2200N Copenhagen, Denmark. hamra@imbg.ku.dk

Abstract

Twin-ribozyme introns are formed by two ribozymes belonging to the group I family and occur in some ribosomal RNA transcripts. The group I-like ribozyme, GIR1, liberates the 5' end of a homing endonuclease messenger RNA in the slime mold Didymium iridis. We demonstrate that this cleavage occurs by a transesterification reaction with the joining of the first and the third nucleotide of the messenger by a 2',5'-phosphodiester linkage. Thus, a group I-like ribozyme catalyzes an RNA branching reaction similar to the first step of splicing in group II introns and spliceosomal introns. The resulting short lariat, by forming a protective 5' cap, might have been useful in a primitive RNA world.

PMID:
16141078
[PubMed - indexed for MEDLINE]
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