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Cryo-EM structure of mammalian RNA polymerase II in complex with human RPAP2

Isaac Fianu1, Christian Dienemann1, Shintaro Aibara1

  • 1Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.

Communications Biology
|May 22, 2021
PubMed

Insights

The conserved factor RPAP2 is crucial for RNA polymerase II (Pol II) nuclear import. Its structure reveals RPAP2 binds Pol II, preventing DNA binding during transcription initiation.

Area of Science:

  • Molecular Biology
  • Structural Biology
  • Biochemistry

Background:

  • Nuclear import of RNA polymerase II (Pol II) is essential for gene expression.
  • The conserved factor RPAP2 plays a critical role in this process.

Purpose of the Study:

  • To determine the structural basis of RPAP2 interaction with mammalian Pol II.
  • To understand the functional implications of this interaction during transcription.

Main Methods:

  • Cryo-electron microscopy (cryo-EM) was used to obtain the structure.
  • The structure of mammalian Pol II in complex with human RPAP2 was resolved at 2.8 Å resolution.

Main Results:

  • RPAP2 binds to a specific site between the RPB1 and RPB5 subunits of Pol II.
  • This binding site is incompatible with the binding of downstream DNA.
  • RPAP2 is displaced from Pol II upon the formation of a transcription pre-initiation complex.

Conclusions:

  • RPAP2 acts as a gatekeeper, regulating Pol II entry into the nucleus and its availability for transcription.
  • The structural data provides insights into the dynamic regulation of Pol II during transcription initiation.

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