Exoribonuclease R in Mycoplasma genitalium can carry out both RNA processing and degradative functions and is sensitive to RNA ribose methylation

Maureen S. Lalonde, Yuhong Zuo, Jianwei Zhang, Xin Gong, Shaohui Wu, Arun Malhotra, Zhongwei Li

Research output: Contribution to journalArticle

26 Scopus citations


Mycoplasma genitalium, a small bacterium having minimal genome size, has only one identified exoribonuclease, RNase R (MgR). We have purified MgR to homogeneity, and compared its RNA degradative properties to those of its Escherichia coli homologs RNase R (EcR) and RNase II (EcII). MgR is active on a number of substrates including oligoribonucleotides, poly(A), rRNA, and precursors to tRNA. Unlike EcR, which degrades rRNA and pre-tRNA without formation of intermediate products, MgR appears sensitive to certain RNA structural features and forms specific products from these stable RNA substrates. The 3′-ends of two MgR degradation products of 23S rRNA were mapped by RT-PCR to positions 2499 and 2553, each being 1 nucleotide downstream of a 2′-O-methylation site. The sensitivity of MgR to ribose methylation is further demonstrated by the degradation patterns of 16S rRNA and a synthetic methylated oligoribonucleotide. Remarkably, MgR removes the 3′-trailer sequence from a pre-tRNA, generating product with the mature 3′-end more efficiently than EcII does. In contrast, EcR degrades this pre-tRNA without the formation of specific products. Our results suggest that MgR shares some properties of both EcR and EcII and can carry out a broad range of RNA processing and degradative functions. Published by Cold Spring Harbor Laboratory Press.

Original languageEnglish
Pages (from-to)1957-1968
Number of pages12
Issue number11
StatePublished - Nov 1 2007



  • Mycoplasma
  • Ribose methylation
  • RNA degradation
  • RNase R
  • tRNA processing

ASJC Scopus subject areas

  • Genetics
  • Molecular Biology

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