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The Role of Nuclear Cap Binding Protein Cbc1p of Yeast in mRNA Termination and Degradation

Das, Biswadip and Guo, Zijian and Russo, Patrick and Chartrand, Patrick and Sherman, Fred (2000) The Role of Nuclear Cap Binding Protein Cbc1p of Yeast in mRNA Termination and Degradation. Molecular and Cellular Biology, 20 (8). pp. 2827-2838. ISSN 0270-7306.

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The cyc1-512 mutation in Saccharomyces cerevisiae causes a 90% reduction in the level of iso-1-cytochrome c because of the lack of a proper 3'-end-forming signal, resulting in low levels of eight aberrantly long cyc1-512 mRNAs which differ in length at their 3' termini. cyc1-512 can be suppressed by deletion of either of the nonessential genes CBC1 and CBC2, which encode the CBP80 and CBP20 subunits of the nuclear cap binding complex, respectively, or by deletion of the nonessential gene UPF1, which encodes a major component of the mRNA surveillance complex. The upf1-Delta deletion suppressed the cyc1-512 defect by diminishing degradation of the longer subset of cyc1-512 mRNAs, suggesting that downstream elements or structures occurred in the extended 3' region, similar to the downstream elements exposed by transcripts bearing premature nonsense mutations. On the other hand, suppression of cyc1-512 defects by cbc1-Delta occurred by two different mechanisms. The levels of the shorter cyc1-512 transcripts were enhanced in the cbc1-Delta mutants by promoting 3'-end formation at otherwise-weak sites, whereas the levels of the longer cyc1-512 transcripts, as well as of all mRNAs, were slightly enhanced by diminishing degradation. Furthermore, cbc1-Delta greatly suppressed the degradation of mRNAs and other phenotypes of a rat7-1 strain which is defective in mRNA export. We suggest that Cbc1p defines a novel degradation pathway that acts on mRNAs partially retained in nuclei.

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Additional Information:Copyright © 2000, American Society for Microbiology. Received 16 September 1999/Returned for modification 20 November 1999/Accepted 16 January 2000 We thank Michael R. Culbertson (University of Wisconsin) for the UPF1 disrupter and other UPF1 plasmids; Charles N. Cole (Dartmouth Medical School) for the rat7-1 and RAT7+ strains; V. Raju (Department of Cardiology, University of Rochester) for advice on Northern blot analysis; Edward Pagani (Pfizer Inc., Groton, Conn.) for a generous gift of thiolutin; Jay R. Greenberg (Department of Biochemistry and Biophysics, University of Rochester), Ding-Fang Yun (Cadus Pharmaceutical Corp., Tarrytown, N.Y.), Alan Sachs (University of California, Berkeley), Roy Parker (University of Arizona), Scott Butler (University of Rochester), Stuart Peltz (University of Medicine and Dentistry of New Jersey), and Allan Jacobson (University of Massachusetts Medical School) for helpful discussions; and Satarupa Das for assistance in the preparation of the cbc2-Delta disruptant. This investigation was supported by NIH research grant GM12702 (to F.S.) and by an FCAR Canadian Postdoctoral Fellowship (to P.C.).
Issue or Number:8
Record Number:CaltechAUTHORS:DASmcb00
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ID Code:2800
Deposited By: Archive Administrator
Deposited On:27 Apr 2006
Last Modified:02 Oct 2019 22:56

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