Mpe1 senses the binding of pre-mRNA and controls 3' end processing by CPF

Area of Science:

• Molecular Biology
• RNA Processing
• Gene Expression Regulation

Background:

• Eukaryotic messenger RNA (mRNA) 3' end processing is crucial for transcript maturation and stability.
• The cleavage and polyadenylation specificity factor (CPF) complex regulates mRNA 3' end formation, a tightly controlled process.
• Accurate CPF function is essential for maintaining RNA processing fidelity and preventing aberrant transcription.

Purpose of the Study:

• To elucidate the structural and functional role of the Mpe1 subunit within the CPF complex.
• To investigate how Mpe1 influences CPF activity and its interaction with nascent pre-mRNA.
• To determine the in vivo consequences of Mpe1 dysfunction on RNA processing and transcription.

Main Methods:

• Cryo-electron microscopy (cryo-EM) was employed to visualize the structure of yeast CPF.
• Biochemical assays were used to assess CPF endonuclease activity and RNA binding.
• In vivo studies involved Mpe1 depletion and mutation to evaluate effects on transcription termination.

Main Results:

• The Mpe1 subunit directly contacts the polyadenylation signal sequence on nascent pre-mRNA.
• Mpe1 binding to RNA activates CPF endonuclease activity and controls polyadenylation site selection.
• Mpe1 depletion or mutation results in significant defects in transcription termination by RNA polymerase II.

Conclusions:

• Mpe1 is a critical component of CPF, directly mediating RNA interaction and activating its enzymatic functions.
• Mpe1 plays a vital role in ensuring accurate 3' end processing and timely transcription termination.
• Dysregulation of Mpe1 leads to transcription interference, highlighting its importance in maintaining genome integrity.