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Xenopus U8 snoRNA binding protein is a conserved nuclear decapping enzyme
Trina Ghosh1, Brian Peterson, Nenad Tomasevic
1National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, Genetics and Biochemistry Branch, Building 8, Room 106, Bethesda, MD 20892, USA.
Molecular Cell
|April 1, 2004
Summary
A novel protein, X29, binds U8 RNA and removes its methylated cap, regulating its levels for ribosome biogenesis. This discovery identifies a conserved family of nuclear decapping proteins. Keywords: X29 protein, U8 RNA, ribosome biogenesis, decapping.
Area of Science:
- Molecular Biology
- Biochemistry
- Cell Biology
Background:
- U8 small nucleolar ribonucleoprotein (snoRNP) is crucial for mature 5.8S and 28S rRNA accumulation in vertebrates.
- Understanding proteins interacting with U8 RNA is key to elucidating its role in ribosome biogenesis.
Purpose of the Study:
- To identify and characterize proteins that bind U8 RNA with high specificity.
- To understand the function of the Xenopus 29 kDa protein (X29) in U8 RNA regulation and ribosome biogenesis.
Main Methods:
- Protein-RNA binding assays to confirm high-affinity interaction between X29 and U8 RNA.
- Biochemical assays to determine the enzymatic activity of recombinant X29 protein.
- Cellular localization studies of X29 in Xenopus tissue culture cells.
Main Results:
- Xenopus 29 kDa protein (X29) was characterized, showing high-affinity binding to U8 RNA.
- X29 and its human homolog possess NUDIX domain-dependent diphosphatase activity, capable of removing methylated caps (m7G and m227G) from U8 and other RNAs in vitro.
- X29 localizes primarily to the nucleolus in Xenopus cells.
Conclusions:
- X29 is a nucleolar decapping enzyme that specifically binds U8 RNA.
- X29 and its homologs represent a conserved family of nuclear decapping proteins.
- This family likely plays a role in regulating the levels of U8 snoRNA and other nuclear RNAs with methylated caps, impacting ribosome biogenesis.