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RPAP2 regulates a transcription initiation checkpoint by inhibiting assembly of pre-initiation complex

Xinxin Wang1, Yilun Qi2, Zhenning Wang2

  • 1Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering, Department of Biochemistry and Biophysics, School of Life Sciences, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai 200032, China; The International Co-laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, China, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai 200032, China; Human Phenome Institute, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai 200433, China.

Cell Reports
|April 27, 2022
PubMed

Insights

RNA Pol II-associated protein 2 (RPAP2) inhibits transcription initiation by blocking pre-initiation complex assembly. This protein acts as a gatekeeper, ensuring precise regulation of gene expression.

Area of Science:

  • Molecular Biology
  • Gene Regulation
  • Biochemistry

Background:

  • RNA polymerase II (Pol II) transcription requires precise regulation in metazoans.
  • RNA Pol II-associated protein 2 (RPAP2) was previously known for Pol II transport and dephosphorylation.

Purpose of the Study:

  • To investigate the precise role and mechanism of RPAP2 in transcription regulation.
  • To determine if RPAP2's phosphatase activity is essential for its function.

Main Methods:

  • Structural analysis of RPAP2-Pol II complex.
  • In vitro transcription assays.
  • Cellular studies on RPAP2-deficient cells.

Main Results:

  • RPAP2 binds Pol II but lacks detectable phosphatase activity.
  • Structural data reveals steric clashes preventing pre-initiation complex (PIC) assembly.
  • RPAP2 inhibits Pol II-TFIIF interaction and impairs transcription initiation.
  • RPAP2 loss causes TFIIF and Pol II accumulation at promoters.

Conclusions:

  • RPAP2 acts as a gatekeeper inhibiting PIC assembly and transcription initiation, independent of its phosphatase activity.
  • RPAP2 plays a critical role in regulating transcription through a novel mechanism.
  • The findings suggest RPAP2's involvement in a transcription checkpoint.
Keywords:
CP: Molecular biologyPol IIRPAP2pre-initiation complextranscription initiation

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