Arabidopsis thaliana exosome subunit AtRrp4p is a hydrolytic 3′→5′ exonuclease containing S1 and KH RNA-binding domains |
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Authors: | Julia A. Chekanova James A. Dutko I. Saira Mian Dmitry A. Belostotsky |
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Affiliation: | Department of Biological Sciences, State University of New York at Albany, 1400 Washington Avenue, Albany, NY 12222, USA and 1.Radiation Biology and Environmental Toxicology Group, Life Sciences Division, Lawrence Berkeley National Laboratory, Cyclotron Road, Berkeley, CA 94720, USA |
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Abstract: | The exosome, an evolutionarily conserved complex of multiple 3′→5′ exoribonucleases, is responsible for a variety of RNA processing and degradation events in eukaryotes. In this report Arabidopsis thaliana AtRrp4p is shown to be an active 3′→5′ exonuclease that requires a free 3′-hydroxyl and degrades RNA hydrolytically and distributively, releasing nucleoside 5′-monophosphate products. AtRrp4p behaves as an ~500 kDa species during sedimentation through a 10–30% glycerol gradient, co-migrating with AtRrp41p, another exosome subunit, and it interacts in vitro with AtRrp41p, suggesting that it is also present in the plant cell as a subunit of the exosome. We found that, in addition to a previously reported S1-type RNA-binding domain, members of the Rrp4p family of proteins contain a KH-type RNA-binding domain in the C-terminal half and show that either domain alone can bind RNA. However, only the full-length protein is capable of degrading RNA and interacting with AtRrp41p. |
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