A protein encoded by a group I intron in Aspergillus nidulans directly assists RNA splicing and is a DNA endonuclease
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Edited by Thomas W. Cline, University of California, Berkeley, CA, and approved June 24, 1997 (received for review April 14, 1997)
Abstract
Some group I introns self-splice in vitro, but almost all are thought to be assisted by proteins in vivo. Mutational analysis has shown that the splicing of certain group I introns depends upon a maturase protein encoded by the intron itself. However the effect of a protein on splicing can be indirect. We now provide evidence that a mitochondrial intron-encoded protein from Aspergillus nidulans directly facilitates splicing in vitro. This demonstrates that a maturase is an RNA splicing protein. The protein-assisted reaction is as fast as that of any other known group I intron. Interestingly the protein is also a DNA endonuclease, an activity required for intron mobilization. Mobile elements frequently encode proteins that promote their propagation. Intron-encoded proteins that also assist RNA splicing would facilitate both the transposition and horizontal transmission of introns.
Footnotes
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↵ * To whom reprint requests should be addressed. e-mail: waring{at}astro.ocis.temple.edu.
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This paper was submitted directly (Track II) to the Proceedings Office.
- Copyright © 1997, The National Academy of Sciences of the USA
