The physiological role of RNase T can be explained by its unusual substrate specificity.

Yuhong Zuo, Murray P Deutscher

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

Escherichia coli RNase T, the enzyme responsible for the end-turnover of tRNA and for the 3' maturation of 5 S and 23 S rRNAs and many other small, stable RNAs, was examined in detail with respect to its substrate specificity. The enzyme was found to be a single-strand-specific exoribonuclease that acts in the 3' to 5' direction in a non-processive manner. However, although other Escherichia coli exoribonucleases stop several nucleotides downstream of an RNA duplex, RNase T can digest RNA up to the first base pair. The presence of a free 3'-hydroxyl group is required for the enzyme to initiate digestion. Studies with RNA homopolymers and a variety of oligoribonucleotides revealed that RNase T displays an unusual base specificity, discriminating against pyrimidine and, particularly, C residues. Although RNase T appears to bind up to 10 nucleotides in its active site, its specificity is defined largely by the last 4 residues. A single 3'-terminal C residue can reduce RNase T action by >100-fold, and 2-terminal C residues essentially stop the enzyme. In vivo, the substrates of RNase T are similar in that they all contain a double-stranded stem followed by a single-stranded 3' overhang; yet, the action of RNase T on these substrates differs. The substrate specificity described here helps to explain why the different substrates yield different products, and why certain RNA molecules are not substrates at all.

Original languageEnglish
Pages (from-to)29654-29661
Number of pages8
JournalJournal of Biological Chemistry
Volume277
Issue number33
StatePublished - Aug 16 2002

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Substrate Specificity
Substrates
RNA
Exoribonucleases
Enzymes
Escherichia coli
Nucleotides
Oligoribonucleotides
Transfer RNA
exoribonuclease T
Homopolymerization
Base Pairing
Hydroxyl Radical
Digestion
Catalytic Domain
Molecules

ASJC Scopus subject areas

  • Biochemistry

Cite this

The physiological role of RNase T can be explained by its unusual substrate specificity. / Zuo, Yuhong; Deutscher, Murray P.

In: Journal of Biological Chemistry, Vol. 277, No. 33, 16.08.2002, p. 29654-29661.

Research output: Contribution to journalArticle

Zuo, Yuhong ; Deutscher, Murray P. / The physiological role of RNase T can be explained by its unusual substrate specificity. In: Journal of Biological Chemistry. 2002 ; Vol. 277, No. 33. pp. 29654-29661.
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