Cwc2 and its human homologue RBM22 promote an active conformation of the spliceosome catalytic centre |
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Authors: | Rasche Nicolas Dybkov Olexandr Schmitzová Jana Akyildiz Berktan Fabrizio Patrizia Lührmann Reinhard |
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Affiliation: | 1.Department of Cellular Biochemistry, Max-Planck-Institute of Biophysical Chemistry, Göttingen, Germany |
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Abstract: | RNA-structural elements play key roles in pre-mRNA splicing catalysis; yet, the formation of catalytically competent RNA structures requires the assistance of spliceosomal proteins. We show that the S. cerevisiae Cwc2 protein functions prior to step 1 of splicing, and it is not required for the Prp2-mediated spliceosome remodelling that generates the catalytically active B complex, suggesting that Cwc2 plays a more sophisticated role in the generation of a functional catalytic centre. In active spliceosomes, Cwc2 contacts catalytically important RNA elements, including the U6 internal stem-loop (ISL), and regions of U6 and the pre-mRNA intron near the 5' splice site, placing Cwc2 at/near the spliceosome's catalytic centre. These interactions are evolutionarily conserved, as shown by studies with Cwc2's human counterpart RBM22, indicating that Cwc2/RBM22-RNA contacts are functionally important. We propose that Cwc2 induces an active conformation of the spliceosome's catalytic RNA elements. Thus, the function of RNA-RNA tertiary interactions within group II introns, namely to induce an active conformation of domain V, may be fulfilled by proteins that contact the functionally analogous U6-ISL, within the spliceosome. |
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Keywords: | catalytic centre Cwc2 RBM22 spliceosome U6‐ISL |
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