Elevated Levels of Era GTPase Improve Growth, 16S rRNA Processing, and 70S Ribosome Assembly ofEscherichia coliLacking Highly Conserved Multifunctional YbeY Endoribonuclease
ABSTRACTYbeY is a highly conserved, multifunctional endoribonuclease that plays a significant role in ribosome biogenesis and has several additional roles. Here we show that overexpression of the conserved GTPase Era inEscherichia colipartially suppresses the growth defect of a ΔybeYstrain while improving 16S rRNA processing and 70S ribosome assembly. This suppression requires both the ability of Era to hydrolyze GTP and the function of three exoribonucleases, RNase II, RNase R, and RNase PH, suggesting a model for the action of Era. Overexpression ofVibrio choleraeEra similarly partially suppresses the defects of anE. coliΔybeYstrain, indicating that this property of Era is conserved in bacteria other thanE. coli.IMPORTANCEThis work provides insight into the critical, but still incompletely understood, mechanism of processing of theE. coli16S rRNA 3′ terminus. The highly conserved GTPase Era is known to bind to the precursor of the 16S rRNA near its 3′ end. Both the endoribonuclease YbeY, which binds to Era, and four exoribonucleases have been implicated in this 3′-end processing. The results reported here offer additional insights into the role of Era in 16S rRNA 3′-end maturation and into the relationship between the action of the endoribonuclease YbeY and that of the four exoribonucleases. This study also hints at why YbeY is essential only in some bacteria and suggests that YbeY could be a target for a new class of antibiotics in these bacteria.