Mode of action of RNase BN/RNase Z on tRNA precursors: RNase BN does not remove the CCA sequence from tRNA

Tanmay Dutta, Murray P. Deutscher

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

RNase BN, the Escherichia coli homolog of RNase Z, was previously shown to act as both a distributive exoribonuclease and an endoribonuclease on model RNA substrates and to be inhibited by the presence of a 3′-terminal CCA sequence. Here, we examined the mode of action of RNaseBNon bacteriophage and bacterial tRNA precursors, particularly in light of a recent report suggesting that RNase BN removes CCA sequences (Takaku, H., and Nashimoto, M. (2008) Genes Cells 13, 1087-1097). We show that purified RNase BN can process both CCAless and CCA-containing tRNA precursors. On CCA-less precursors, RNase BN cleaved endonucleolytically after the discriminator nucleotide to allow subsequent CCA addition. On CCA-containing precursors, RNase BN acted as either an exoribonuclease or endoribonuclease depending on the nature of the added divalent cation. Addition of Co2+ resulted in higher activity and predominantly exoribonucleolytic activity, whereas in the presence of Mg 2+, RNase BN was primarily an endoribonuclease. In no case was any evidence obtained for removal of the CCA sequence. Certain tRNA precursors were extremely poor substrates under any conditions tested. These findings provide important information on the ability of RNase BN to processtRNAprecursors and help explain the known physiological properties of this enzyme. In addition, they call into question the removal of CCA sequences by RNase BN.

Original languageEnglish (US)
Pages (from-to)22874-22881
Number of pages8
JournalJournal of Biological Chemistry
Volume285
Issue number30
DOIs
StatePublished - Jul 23 2010

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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