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Alternative 3 -end processing of U5 snRNA by RNase III

Summary: Alternative 3 -end processing of U5
snRNA by RNase III
Guillaume Chanfreau,1,3
Sherif Abou Elela,2
Manuel Ares, Jr.,2
and Christine Guthrie1,4
Department of Biochemistry and Biophysics, University of California School of Medicine, San Francisco, California
94143-0448 USA; 2
Center for the Molecular Biology of RNA, Sinsheimer Laboratories, University of California,
Santa Cruz, California 95064 USA
The cellular components required to form the 3 ends of small nuclear RNAs are unknown. U5 snRNA from
Saccharomyces cerevisiae is found in two forms that differ in length at their 3 ends (U5L and U5S). When
added to a yeast cell free extract, synthetic pre-U5 RNA bearing downstream genomic sequences is processed
efficiently and accurately to generate both mature forms of U5. The two forms of U5 are produced in vitro by
alternative 3 -end processing. A temperature-sensitive mutation in the RNT1 gene encoding RNase III blocks
accumulation of U5L in vivo. In vitro, alternative cleavage of the U5 precursor by RNase III determines the
choice between the two multistep pathways that lead to U5L and U5S, one of which (U5L) is strictly
dependent on RNase III. These results identify RNase III as a trans-acting factor involved in 3 -end formation
of snRNA and show how RNase III might regulate alternative RNA processing pathways.


Source: Abou Elela, Sherif - Département de Microbiologie et d'Infectiologie, Université de Sherbrooke
Ares Jr., Manny - Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz


Collections: Biology and Medicine