Publications by authors named "K Hartmuth"
Human spliceosomes contain numerous proteins absent in yeast, whose functions remain largely unknown. Here we report a 3D cryo-EM structure of the human spliceosomal C complex at 3.4 Å core resolution and 4.
View Article and Find Full Text PDFThe U2 small nuclear ribonucleoprotein (snRNP) has an essential role in the selection of the precursor mRNA branch-site adenosine, the nucleophile for the first step of splicing. Stable addition of U2 during early spliceosome formation requires the DEAD-box ATPase PRP5. Yeast U2 small nuclear RNA (snRNA) nucleotides that form base pairs with the branch site are initially sequestered in a branchpoint-interacting stem-loop (BSL), but whether the human U2 snRNA folds in a similar manner is unknown.
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- The spliceosome's U2/U6 RNA core relies on both RNA interactions and spliceosomal proteins for its stable 3D structure.
- Mutations in certain U6 nucleotides showed that while some RNA interactions had minimal impact on splicing, others were crucial, especially U6-G60, whose removal completely halted splicing.
- The findings suggest that while RNA stacking interactions enhance coordination of metal M2 crucial for splicing, the overall function of the RNA core is supported by a combination of RNA-RNA and Protein-RNA interactions.
Article Synopsis
- The spliceosome is a complex that removes introns from pre-mRNA and the study provides a detailed 3D structure of the human B spliceosome at high resolution.
- The B spliceosome is shown to be activated but not ready for the splicing reaction, indicating a functional blockade before the first step.
- By analyzing the conformational changes within the spliceosome, researchers identified eight dynamic states that help understand how various components interact and work together for its activation.
The RNA helicase Prp2 facilitates the remodeling of the spliceosomal B complex to the catalytically activated B* complex just before step one of splicing. As a high-resolution cryo-EM structure of the B* complex is currently lacking, the precise spliceosome remodeling events mediated by Prp2 remain poorly understood. To investigate the latter, we used chemical structure probing to compare the RNA structure of purified yeast B and B* complexes.
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