The vacB gene required for virulence in Shigella flexneri and Escherichia coli encodes the exoribonuclease RNase R

Zhuan Fen Cheng, Yuhong Zuo, Zhongwei Li, Kenneth E. Rudd, Murray P. Deutscher

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vacB, a gene previously shown to be required for expression of virulence in Shigella and enteroinvasive Escherichia coli, has been found to encode the 3'-5' exoribonuclease, RNase R. Thus, cloning of E. coli vacB led to overexpression of RNase R activity, and partial deletion or interruption of the cloned gene abolished this overexpression. Interruption of the chromosomal copy of vacB eliminated endogenous RNase R activity; however, the absence of RNase R by itself had no effect on cell growth. In contrast, cells lacking both RNase R and polynucleotide phosphorylase were found to be inviable. These data indicate that RNase R participates in an essential cell function in addition to its role in virulence. The identification of the vacB gene product as RNase R should aid in understanding how the virulence phenotype in enterobacteria is expressed and regulated. On the basis of this information we propose that vacB be renamed rnr.

Original languageEnglish (US)
Pages (from-to)14077-14080
Number of pages4
JournalJournal of Biological Chemistry
Issue number23
StatePublished - Jun 5 1998


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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