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A complex pathway for 3' processing of the yeast U3 snoRNA
Joanna Kufel1, Christine Allmang, Loredana Verdone
1Institute of Cell and Molecular Biology, Swann Building, King's Buildings, The University of Edinburgh, Edinburgh EH9 3JR, UK.
Nucleic Acids Research
|November 25, 2003
Summary
The Lsm proteins are essential for the 3' processing of U3 small nucleolar RNA (snoRNA) in yeast. These proteins, along with Lhp1p, stabilize precursor U3 RNA, preventing degradation.
Area of Science:
- Molecular Biology
- RNA Processing
- Yeast Genetics
Background:
- Mature U3 snoRNA is produced from 3'-extended precursors through cleavage and trimming.
- These precursors are typically stabilized by the La homologue, Lhp1p.
Purpose of the Study:
- To investigate the role of nuclear Lsm proteins in the 3' processing of U3 snoRNA.
- To understand the interplay between Lsm proteins and Lhp1p in U3 snoRNA precursor stabilization.
Main Methods:
- Depletion of essential Lsm proteins (Lsm2-5p, Lsm8p) in yeast.
- Co-precipitation assays using TAP-tagged Lsm3p and Sm proteins.
- Analysis of U3 snoRNA precursor and mature species by RNA analysis.
Main Results:
- Depletion of Lsm proteins led to the loss of normal 3'-extended U3 precursors and accumulation of truncated fragments.
- Lsm proteins associate with pre-U3, and this association is interdependent with Lhp1p binding.
- Sm proteins co-precipitated pre-U3 only in Lhp1p-deficient strains.
Conclusions:
- The Lsm2-8p complex, with Lhp1p, acts as a chaperone to stabilize pre-U3 RNA during 3' processing.
- The Sm complex may serve as a backup stabilization mechanism when Lhp1p is absent.