title: The vacB gene required for virulence in Shigella flexneri and Escherichia coli encodes the exoribonuclease RNase R.
abstract: 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.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Miami, Florida 33101-6129, USA.
authors.forename: Z F
authors.initials: ZF
authors.lastname: Cheng
authors.forename: Y
authors.initials: Y
authors.lastname: Zuo
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.forename: K E
authors.initials: KE
authors.lastname: Rudd
authors.forename: M P
authors.initials: MP
authors.lastname: Deutscher
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology; D003001:Cloning, Molecular; D004722:Endoribonucleases / Q000235:genetics* / Q000502:physiology; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins; D005095:Exoribonucleases; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D010641:Phenotype; D011061:Poly A / Q000378:metabolism; D011117:Polyribonucleotide Nucleotidyltransferase / Q000502:physiology; D015183:Restriction Mapping; D012763:Shigella flexneri / Q000201:enzymology* / Q000235:genetics; D014161:Transduction, Genetic / Q000235:genetics; D014774:Virulence / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C489683:rnr protein, E coli; C077231:VacB protein, Shigella flexneri; D011061:Poly A; D011117:Polyribonucleotide Nucleotidyltransferase; D004722:Endoribonucleases; D005095:Exoribonucleases; C080868:ribonuclease R