Department of Cell Biology and Molecular Genetics, University of Maryland at College Park, College Park, MD 20742, USA; Research Institute for Drug Development, Pusan National University, Busan 46241, South Korea
Mona W. Orr
Department of Cell Biology and Molecular Genetics, University of Maryland at College Park, College Park, MD 20742, USA
Husan Turdiev
Department of Cell Biology and Molecular Genetics, University of Maryland at College Park, College Park, MD 20742, USA
Conor C. Jenkins
Department of Cell Biology and Molecular Genetics, University of Maryland at College Park, College Park, MD 20742, USA
Justin D. Lormand
CSSB Centre for Structural Systems Biology, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
Tanner M. Myers
Department of Cell Biology and Molecular Genetics, University of Maryland at College Park, College Park, MD 20742, USA
Audrey Andy Burnim
Intramural Research Program, NLM, NIH, Bethesda, MD 20894, USA
Jared.A. Carter
Department of Cell Biology and Molecular Genetics, University of Maryland at College Park, College Park, MD 20742, USA
Warren C. Kung
Department of Cell Biology and Molecular Genetics, University of Maryland at College Park, College Park, MD 20742, USA
Xiaofang Jiang
Intramural Research Program, NLM, NIH, Bethesda, MD 20894, USA
Holger Sondermann
CSSB Centre for Structural Systems Biology, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
Wade C. Winkler
Department of Cell Biology and Molecular Genetics, University of Maryland at College Park, College Park, MD 20742, USA
Vincent T. Lee
Department of Cell Biology and Molecular Genetics, University of Maryland at College Park, College Park, MD 20742, USA; Corresponding author
Summary: RNA degradation is a central process required for transcriptional regulation. Eventually, this process degrades diribonucleotides into mononucleotides by specific diribonucleases. In Escherichia coli, oligoribonuclease (Orn) serves this function and is unique as the only essential exoribonuclease. Yet, related organisms, such as Pseudomonas aeruginosa, display a growth defect but are viable without Orn, contesting its essentiality. Here, we take advantage of P. aeruginosa orn mutants to screen for suppressors that restore colony morphology and identified yciV. Purified YciV (RNase AM) exhibits diribonuclease activity. While RNase AM is present in all γ-proteobacteria, phylogenetic analysis reveals differences that map to the active site. RNase AMPa expression in E. coli eliminates the necessity of orn. Together, these results show that diribonuclease activity prevents toxic diribonucleotide accumulation in γ-proteobacteria, suggesting that diribonucleotides may be utilized to monitor RNA degradation efficacy. Because higher eukaryotes encode Orn, these observations indicate a conserved mechanism for monitoring RNA degradation.
