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RNase G of Escherichia coli exhibits only limited functional overlap with its essential homologue, RNase E
Author(s) -
Ow Maria C.,
Perwez Tariq,
Kushner Sidney R.
Publication year - 2003
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2003.03587.x
Subject(s) - rnase mrp , rnase p , endoribonuclease , rnase ph , biology , transfer rna , degradosome , ribosomal rna , rna , messenger rna , rnase h , ribonuclease iii , exosome complex , mutant , microbiology and biotechnology , genetics , gene , rna interference
Summary RNase G ( rng ) is an E. coli endoribonuclease that is homologous to the catalytic domain of RNase E ( rne ), an essential protein that is a major participant in tRNA maturation, mRNA decay, rRNA processing and M1 RNA processing. We demonstrate here that whereas RNase G inefficiently participates in the degradation of mRNAs and the processing of 9S rRNA, it is not involved in either tRNA or M1 RNA processing. This conclusion is supported by the fact that inactivation of RNase G alone does not affect 9S rRNA processing and only leads to minor changes in mRNA half‐lives. However, in rng rne double mutants mRNA decay and 9S rRNA processing are more defective than in either single mutant. Conversely, increasing RNase G levels in an rne‐1 rng::cat double mutant, proportionally increased the extent of 9S rRNA processing and decreased the half‐lives of specific mRNAs. In contrast, variations in the amount of RNase G did not alter tRNA processing under any circumstances. Thus, the failure of RNase G to complement rne mutations, even when overproduced at high levels, apparently results from its inability to substitute for RNase E in the maturation of tRNAs.