E. coli RNase I exhibits a strong Ca2+-dependent inherent double-stranded RNase activity. Issue 9 (22nd April 2021)

• Record Type: Journal Article
• Authors: Grünberg, Sebastian; Coxam, Baptiste; Chen, Tien-Hao; Dai, Nan; Saleh, Lana; Corrêa, Ivan R; Nichols, Nicole M; Yigit, Erbay
• Is Part Of: Nucleic acids research. Volume 49:Issue 9(2021)
• Page Start: 5265
• Page End: 5277
• Publication Date: 2021-04-22
• Subjects: Nucleic acids -- Periodicals; Molecular biology -- Periodicals; 572.805
• DOI: 10.1093/nar/gkab284
• Languages: English
• ISSNs: 0305-1048

Abstract

Abstract: Since its initial characterization, Escherichia coli RNase I has been described as a single-strand specific RNA endonuclease that cleaves its substrate in a largely sequence independent manner. Here, we describe a strong calcium (Ca 2+ )-dependent activity of RNase I on double-stranded RNA (dsRNA), and a Ca 2+ -dependent novel hybridase activity, digesting the RNA strand in a DNA:RNA hybrid. Surprisingly, Ca 2+ does not affect the activity of RNase I on single stranded RNA (ssRNA), suggesting a specific role for Ca 2+ in the modulation of RNase I activity. Mutation of a previously overlooked Ca 2+ binding site on RNase I resulted in a gain-of-function enzyme that is highly active on dsRNA and could no longer be stimulated by the metal. In summary, our data imply that native RNase I contains a bound Ca 2+, allowing it to target both single- and double-stranded RNAs, thus having a broader substrate specificity than originally proposed for this traditional enzyme. In addition, the finding that the dsRNase activity, and not the ssRNase activity, is associated with the Ca 2+ -dependency of RNase I may be useful as a tool in applied molecular biology.