Abstract |
RNase R and RNase II are the two representatives from the RNR family of processive, 3' to 5' exoribonucleases in Escherichia coli. Although RNase II is specific for single-stranded RNA, RNase R readily degrades through structured RNA. Furthermore, RNase R appears to be the only known 3' to 5' exoribonuclease that is able to degrade through double-stranded RNA without the aid of a helicase activity. Consequently, its functional domains and mechanism of action are of great interest. Using a series of truncated RNase R proteins we show that the cold-shock and S1 domains contribute to substrate binding. The cold-shock domains appear to play a role in substrate recruitment, whereas the S1 domain is most likely required to position substrates for efficient catalysis. Most importantly, the nuclease domain alone, devoid of the cold-shock and S1 domains, is sufficient for RNase R to bind and degrade structured RNAs. Moreover, this is a unique property of the nuclease domain of RNase R because this domain in RNase II stalls as it approaches a duplex. We also show that the nuclease domain of RNase R binds RNA more tightly than the nuclease domain of RNase II. This tighter binding may help to explain the difference in catalytic properties between RNase R and RNase II.
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Authors | Helen A Vincent, Murray P Deutscher |
Journal | The Journal of biological chemistry
(J Biol Chem)
Vol. 284
Issue 1
Pg. 486-494
(Jan 02 2009)
ISSN: 0021-9258 [Print] United States |
PMID | 19004832
(Publication Type: Journal Article, Research Support, N.I.H., Extramural)
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Chemical References |
- Escherichia coli Proteins
- RNA, Bacterial
- rnr protein, E coli
- Exoribonucleases
- exoribonuclease II
- RNA Helicases
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Topics |
- Catalysis
- Escherichia coli
(enzymology)
- Escherichia coli Proteins
(chemistry, metabolism)
- Exoribonucleases
(chemistry, metabolism)
- Protein Binding
(physiology)
- Protein Structure, Tertiary
(physiology)
- RNA Helicases
(chemistry, metabolism)
- RNA Processing, Post-Transcriptional
(physiology)
- RNA, Bacterial
(chemistry, metabolism)
- Substrate Specificity
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