Mechanisms of Gene Regulation
Chekanova, Julia , Gregory, Brian D. , Hooker, Tanya S. , Kumar, Ravi , Chen, Huaming , Yazaki, Junshi , Alonso, Jose M. , Brukhin, Vladimir , Grossniklaus, Ueli , Ecker, Joseph R. , Belostotsky, Dmitry .
Unique functional specialization of individual subunits of the RNA-processing exosome complex in Arabidopsis.
The exosome is a protein complex that is required for processing, quality control and degradation of a wide variety of RNA species in the nucleus as well as in the cytoplasm. Its core structure, including 6 RNAse PH-like (phosphorolytic) subunits and 3 RNA-binding domain subunits, is remarkably conserved in all Eukaryotes and even Archaea. Recently, the resolution of the human exosome crystal structure has led to the suggestion that in eukaryotes, each subunit has a unique and essential place in the complex, which must function as a whole. In contrast, we find that this is not the case in plants. First, null mutants of several proteins directly authenticated by proteomics as core exosomal subunits have distinct phenotypes in Arabidopsis: embryo lethality, female gametophyte lethality, or in one case, no obvious phenotype. Second, using inducible RNAi knockdowns coupled with whole genome tiling array analyses, we discovered that depletions of two of the core subunits cause overlapping but distinct changes to the transcriptome. These findings demonstrate that exosome subunits in plants, as opposed to animals, are functionally specialized, or/and functional exosome subcomplexes may exist in certain cell types. Tiling array results also indicate that plants extensively employ the RNA quality control mechanism that involves an unconventional polyadenylation reaction that is mechanistically coupled with the degradation by exosome. Further analyses of this quality control pathway, as well as of the nuclear-specific exosome subunits will be presented.
This work was supported by USDA grant 2005-35301-15757 and NSF MCB0424651 to DB, and BDG is a Damon Runyon Fellow supported by the Damon Runyon Cancer Research Foundation.
Log in to add this item to your schedule
1 - University of Missouri - Kansas City, School of Biological Sciences
2 - The Salk Institute for Biological Studies
3 - North Carolina State University, Department of Genetics
4 - University of Zurich
RNA quality control
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM