title: A novel RNase G mutant that is defective in degradation of adhE mRNA but proficient in the processing of 16S rRNA precursor.
abstract: Escherichia coli RNase G, encoded by the rng gene, is involved in both the processing of 16S rRNA precursor and the degradation of adhE mRNA. Consequently, defects in RNase G result in elevation of AdhE levels. Furthermore, the adhR430 mutant strain, DC430, is reported to overproduce the AdhE protein in a manner dependent on the adhC81 mutation. We found that overproduction of AdhE by DC430 was reversed to wild-type levels by introduction of a plasmid carrying the wild-type allele of rng. Mapping by P1-phage-mediated transduction also indicated that a mutation involved in AdhE overproduction was located around the rng region in DC430. DNA sequencing of the rng region revealed that DC430 indeed had a mutation in the rng gene: a G1022 to A transition that caused substitution of Gly341 with Ser and which was named rng430. This lies in the highly conserved region of the RNase E/RNase G family, called high similarity region 2 (HSR2). However, very interestingly, rng430 mutant strains did not accumulate the 16.3S precursor of 16S rRNA unlike rng::cat mutants. We also found that the Rng1 mutant protein, which is truncated in its C-terminal domain encompassing HSR2, exhibited a residual processing activity against the 16S rRNA precursor, when overproduced. These results indicate that the HSR2 of RNase G plays an important role in substrate recognition and/or ribonucleolytic action.
authors.affiliation: Department of Bioengineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8501, Japan. mwachi@bio.titech.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Wachi
authors.forename: N
authors.initials: N
authors.lastname: Kaga
authors.forename: G
authors.initials: G
authors.lastname: Umitsuki
authors.forename: D P
authors.initials: DP
authors.lastname: Clark
authors.forename: K
authors.initials: K
authors.lastname: Nagai
mesh_terms: D000426:Alcohol Dehydrogenase / Q000235:genetics*; D000445:Aldehyde Oxidoreductases / Q000235:genetics*; D019943:Amino Acid Substitution; D001483:Base Sequence; D002874:Chromosome Mapping; D004722:Endoribonucleases / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D009097:Multienzyme Complexes / Q000235:genetics*; D017354:Point Mutation; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012329:RNA, Bacterial / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; D012322:RNA Precursors; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012336:RNA, Ribosomal, 16S; D000426:Alcohol Dehydrogenase; C068383:adhE protein, E coli; D000445:Aldehyde Oxidoreductases; D004722:Endoribonucleases; C081905:rng protein, E coli