Affiliation:
1. Departments of Microbiology and Immunology and Biochemistry and Biophysics
2. University of Rochester School of Medicine and Dentistry, Rochester, New York
Abstract
ABSTRACT
The RNA-processing exosome is a complex of riboexonucleases required for 3′-end formation of some noncoding RNAs and for the degradation of mRNAs in eukaryotes. The nuclear form of the exosome functions in an mRNA surveillance pathway that retains and degrades improperly processed precursor mRNAs within the nucleus. We report here that the nuclear exosome controls the level of
NAB2
mRNA, encoding the nuclear poly(A)
+
-RNA-binding protein Nab2p. Mutations affecting the activity of the nuclear, but not the cytoplasmic, exosome cause an increase in the amount of
NAB2
mRNA.
Cis
- and
trans
-acting mutations that inhibit degradation by the nuclear-exosome subunit Rrp6p result in elevated levels of
NAB2
mRNA. Control of
NAB2
mRNA levels occurs posttranscriptionally and requires a sequence of 26 consecutive adenosines (A
26
) in the
NAB2
3′ untranslated region, which represses
NAB2
3′-end formation and sensitizes the transcript to degradation by Rrp6p. Analysis of
NAB2
mRNA levels in a
nab2
-
1
mutant and in the presence of excess Nab2p indicates that Nab2p activity negatively controls
NAB2
mRNA levels in an A
26
- and Rrp6p-dependent manner. These findings suggest a novel regulatory circuit in which the nuclear exosome controls the level of
NAB2
mRNA in response to changes in the activity of Nab2 protein.
Publisher
American Society for Microbiology
Subject
Cell Biology,Molecular Biology
Cited by
46 articles.
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