The -Encoded Truncated RNase PH Protein Inhibits RNase P Maturation of Pre-tRNAs with Short Leader Sequences in the Absence of RppH.

RNase PH, encoded by the gene, is a 3'→5' exoribonuclease that in participates primarily in the 3' maturation of pre-tRNAs and the degradation of rRNA in stationary-phase cells. Interestingly, the routinely used laboratory strains of MG1655 and W3110 have naturally acquired the allele, encoding a truncated catalytically inactive RNase PH protein which is widely assumed to be benign. Contrary to this assumption, we show that the -encoded Rph-1 protein inhibits RNase P-mediated 5'-end maturation of primary pre-tRNAs with leaders of <5 nucleotides in the absence of RppH, an RNA pyrophosphohydrolase.

Intragenic suppressors of temperature-sensitive rne mutations lead to the dissociation of RNase E activity on mRNA and tRNA substrates in Escherichia coli.

RNase E of Escherichia coli is an essential endoribonuclease that is involved in many aspects of RNA metabolism. Point mutations in the S1 RNA-binding domain of RNase E (rne-1 and rne-3071) lead to temperature-sensitive growth along with defects in 5S rRNA processing, mRNA decay and tRNA maturation. However, it is not clear whether RNase E acts similarly on all kinds of RNA substrates.

RNase Z in Escherichia coli plays a significant role in mRNA decay.

Genetic and biochemical analysis of RNase Z in eukaryotes, such as Arabadopsis thaliana, and prokaryotes like Bacillus subtilis have demonstrated that this endoribonuclease is essential for the maturation of tRNA precursors that do not contain a chromosomally encoded CCA determinant. As all Escherichia coli tRNA transcripts have chromosomally encoded CCA determinants, the function of its putative RNase Z homologue, the product of the elaC gene, is not clear. Here we demonstrate that the E.

RNase G of Escherichia coli exhibits only limited functional overlap with its essential homologue, RNase E.

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.