Upf1 potentially serves as a RING-related E3 ubiquitin ligase via its association with Upf3 in yeast
- Shinya Takahashi1,2,
- Yasuhiro Araki1,3,
- Yuriko Ohya,
- Takeshi Sakuno4,
- Shin-Ichi Hoshino5,
- Kenji Kontani,
- Hiroshi Nishina2, and
- Toshiaki Katada
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan
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↵1 These authors contributed equally to this work.
Abstract
Three Upf proteins are essential to the nonsense-mediated mRNA decay (NMD) pathway. Although these proteins assemble on polysomes for recognition of aberrant mRNAs containing premature termination codons, the significance of this assembly remains to be elucidated. The Cys- and His-rich repeated N terminus (CH domain) of Upf1 has been implicated in its binding to Upf2. Here, we show that CH domain also plays a RING-related role for Upf1 to exhibit E3 ubiquitin ligase activity in yeast. Despite the sequence divergence from typical E3-RING fingers, the CH domain of yeast Upf1 specifically and directly interacted with the yeast E2 Ubc3. Interestingly, Upf1 served as a substrate for the in vitro self-ubiquitination, and the modification required its association with Upf3 rather than Upf2. Substitution of the coordinated Cys and His residues in the CH domain impaired not only self-ubiquitination of Upf1 but also rapid decay of aberrant mRNAs. These results suggest that Upf1 may serve as an E3 ubiquitin ligase upon its association with Upf3 and play an important role in signaling to the NMD pathway.
Keywords
Footnotes
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↵2 Present addresses: Department of Developmental and Regenerative Biology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan;
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↵3 Zentrum fur Molekulare Biologie der Universitat Heidelberg (ZMBH), Im Neuenheimer Feld 282, 69120 Heidelberg, Germany;
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↵4 Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi Bunkyo-ku, Tokyo 113-0032, Japan;
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↵5 Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Nagoya 467-8603, Japan.
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Reprint requests to: Toshiaki Katada, Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan; e-mail: katada{at}mol.f.u-tokyo.ac.jp; fax: 81-3-5841-4751.
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Article published online ahead of print. Article and publication date are at http://www.rnajournal.org/cgi/doi/10.1261/rna.536308.
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- Received March 5, 2008.
- Accepted June 10, 2008.
- Copyright © 2008 RNA Society
