RBBP6 activates the pre-mRNA 3' end processing machinery in humans

Area of Science:

• Molecular Biology
• RNA Processing
• Biochemistry

Background:

• 3' end processing of human messenger RNAs (mRNAs) is vital for transcript localization, translation, and stability.
• This process is primarily mediated by the cleavage and polyadenylation specificity factor (CPSF).
• Precise regulation of pre-mRNA cleavage is essential for maintaining cellular function.

Purpose of the Study:

• To reconstitute and characterize the specific 3' endonuclease activity of human CPSF in vitro.
• To identify and elucidate the role of additional protein factors involved in human mRNA 3' end processing.
• To investigate the interaction and function of RBBP6 in the CPSF complex.

Main Methods:

• Reconstitution of human CPSF endonuclease activity using purified protein components.
• Biochemical assays to assess specific and efficient 3' endonuclease activity.
• Sequence and mutational analyses to determine protein-protein interactions.

Main Results:

• Specific and efficient 3' endonuclease activity of human CPSF was reconstituted with purified proteins.
• The reconstitution required the seven-subunit CPSF, CStF, CFIIm, and RBBP6.
• RBBP6, unlike its yeast homolog, is recruited in an RNA-dependent manner and interacts with WDR33 and CPSF73 subunits.

Conclusions:

• RBBP6 plays a critical, conserved role in human mRNA 3' end processing.
• The interaction of RBBP6 with CPSF is RNA-dependent, highlighting a regulated mechanism for endonuclease activation.
• These findings emphasize the highly controlled nature of CPSF endonuclease activity for maintaining mRNA processing fidelity.