Article abstract
Nature Structural & Molecular Biology 16, 56 - 62 (2008)
Published online: 7 December 2008 | doi:10.1038/nsmb.1528
The exosome contains domains with specific endoribonuclease, exoribonuclease and cytoplasmic mRNA decay activities
Daneen Schaeffer1, Borislava Tsanova1, Ana Barbas2, Filipa Pereira Reis2, Eeshita Ghosh Dastidar1, Maya Sanchez-Rotunno1, Cecília Maria Arraiano2 & Ambro van Hoof1
Abstract
The eukaryotic exosome is a ten-subunit 3' exoribonucleolytic complex responsible for many RNA-processing and RNA-degradation reactions. How the exosome accomplishes this is unknown. Rrp44 (also known as Dis3), a member of the RNase II family of enzymes, is the catalytic subunit of the exosome. We show that the PIN domain of Rrp44 has endoribonucleolytic activity. The PIN domain is preferentially active toward RNA with a 5' phosphate, suggesting coordination of 5' and 3' processing. We also show that the endonuclease activity is important in vivo. Furthermore, the essential exosome subunit Csl4 does not contain any domains that are required for viability, but its zinc-ribbon domain is required for exosome-mediated mRNA decay. These results suggest that specific exosome domains contribute to specific functions, and that different RNAs probably interact with the exosome differently. The combination of an endoRNase and an exoRNase activity seems to be a widespread feature of RNA-degrading machines.
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center-Houston, 6431 Fannin Street, MSB 1.212 Houston, Texas 77030, USA.
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Apartado 127, 2781-901 Oeiras, Portugal.
Correspondence to: Ambro van Hoof1 e-mail: ambro.van.hoof@uth.tmc.edu
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