European Journal of Biochemistry · 1983 · 64 citations · 32 references
Life SciencesMicrobiologyMolecular BiologyNucleic Acid BiochemistryRna BiologyRna ProcessingRibosomal Rna ProcessingRna CleavageEscherichia ColiPre-ribosomal Rna CleavagePrecursor Ribosomal Rna CleavageRibonuclease ChemistryRibonuclease Iii CleavageRibonuclease MechanismsRibosomal Rna Processing In BacteriaSequence-specific Rna Cleavage
9-S RNA is a processing intermediate that accumulates in an RNase E- strain of Escherichia coli. It spans from the RNase III cleavage site, after 23-S rRNA, to the 3' end of the transcript and is derived from rRNA genes which do not contain tRNAs distal to 5-S rRNA. Here, we have studied the processing of 9-S RNA with ribonuclease E. RNase E cleaves 9-S RNA in two sites: one of these is three nucleotides upstream from the 5' end of 5-S rRNA, the other downstream from its 3' end. Both cleavages are probably introduced by the same enzyme, since both cleavages are thermolabile when an extract of a temperature-sensitive RNase E mutant was used for processing in vitro. In order to asses the role of 5' and 3' end precursor-specific sequences in the RNase E reaction, we isolated the molecules lacking nucleotides at the 5' or 3' end. Molecules having the 5' end of 9-S RNA but missing nucleotides from the 3' end (called 8-S RNA) were as good a substrate for RNase E as 9-S, RNA itself. However, molecules having the 3' end of 9-S RNA but the 5' end of p5 (called 7-S RNA), were less efficient substrates for RNase E. Finally, the removal of as little as seven nucleotides from the 5' end of 8-S RNA rendered it almost completely unsuitable as a substrate for RNase E.
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