Molecular basis for the recognition and cleavage of RNA by the bifunctional 5'-3' exo/endoribonuclease RNase J |
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Authors: | Dorléans Audrey Li de la Sierra-Gallay Inés Piton Jérémie Zig Léna Gilet Laetitia Putzer Harald Condon Ciarán |
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Institution: | FRC550, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France. |
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Abstract: | RNase J is a key member of the β-CASP family of metallo-β-lactamases involved in the maturation and turnover of RNAs in prokaryotes. The B.?subtilis enzyme possesses both 5'-3' exoribonucleolytic and endonucleolytic activity, an unusual property for a ribonuclease. Here, we present the crystal structure of T.?thermophilus RNase J bound to a 4 nucleotide RNA. The structure reveals an RNA-binding channel that illustrates how the enzyme functions in 5'-3' exoribonucleolytic mode and how it can function as an endonuclease. A second, negatively charged tunnel leads from the active site, and is ideally located to evacuate the cleaved nucleotide in 5'-3' exonucleolytic mode. We show that B.?subtilis RNase J1, which shows processive behavior on long RNAs, behaves distributively for substrates less than 5 nucleotides in length. We propose a model involving the binding of the RNA to the surface of the β-CASP domain to explain the enzyme's processive action. |
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