Characterization of the RNase R association with ribosomes

Background: In this study we employed the TAP tag purification method coupled with mass spectrometry analysis to identify proteins that co-purify with Escherichia coli RNase R during exponential growth and after temperature downshift. Results: Our initial results suggested that RNase R can interact with bacterial ribosomes. We subsequently confirmed this result using sucrose gradient ribosome profiling joined with western blot analysis. We found that RNase R co-migrates with the single 30S ribosomal subunits. Independent data involving RNase R in the rRNA quality control process allowed us to hypothesize that the RNase R connection with ribosomes has an important physiological role. Conclusions: This study leads us to conclude that RNase R can interact with ribosomal proteins and that this interaction may be a result of this enzyme involvement in the ribosome quality control.