A Novel Mechanism for Ribonuclease Regulation: TRANSFER-MESSENGER RNA (tmRNA) AND ITS ASSOCIATED PROTEIN SmpB REGULATE THE STABILITY OF RNase R* |
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Authors: | Wenxing Liang Murray P Deutscher |
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Institution: | From the Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, Florida 33101 |
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Abstract: | The amount of RNase R, an important degradative exoribonuclease, increases 3–10-fold under a variety of stress conditions. This elevation is due to posttranslational regulation in which the highly unstable RNase R protein becomes stabilized during stress. Here we identify two components of the trans-translation machinery, transfer-messenger RNA (tmRNA) and SmpB, that are responsible for the short half-life of RNase R in exponential phase cells. The absence of either lengthens the half-life of RNase R in vivo >6-fold. SmpB directly interacts with RNase R in vitro and is stimulated by tmRNA. The C-terminal region of RNase R, encompassing its basic region and adjacent S1 domain are required for the interaction; their removal eliminates binding and stabilizes RNase R in vivo. However, the binding of SmpB and tmRNA does not alter RNase R activity. These data define a previously unknown regulatory process in which the stability of an RNase is determined by its interaction with an RNA and an RNA-associated protein. |
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Keywords: | Protein Stability Protein Turnover Protein-Protein Interactions Ribonuclease RNA-Protein Interaction |
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