Download MendeleyStructure of a transcribing RNA polymerase II-U1 snRNP complex.
Zhang, S., Aibara, S., Vos, S.M., Agafonov, D.E., Luhrmann, R., Cramer, P.(2021) Science 371: 305-309
- PubMed: 33446560
- DOI: https://doi.org/10.1126/science.abf1870
- Primary Citation of Related Structures:
7B0Y - PubMed Abstract:
To initiate cotranscriptional splicing, RNA polymerase II (Pol II) recruits the U1 small nuclear ribonucleoprotein particle (U1 snRNP) to nascent precursor messenger RNA (pre-mRNA). Here, we report the cryo-electron microscopy structure of a mammalian transcribing Pol II-U1 snRNP complex. The structure reveals that Pol II and U1 snRNP interact directly. This interaction positions the pre-mRNA 5' splice site near the RNA exit site of Pol II. Extension of pre-mRNA retains the 5' splice site, leading to the formation of a "growing intron loop." Loop formation may facilitate scanning of nascent pre-mRNA for the 3' splice site, functional pairing of distant intron ends, and prespliceosome assembly. Our results provide a starting point for a mechanistic analysis of cotranscriptional spliceosome assembly and the biogenesis of mRNA isoforms by alternative splicing.
Organizational Affiliation:
Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
