Cleavage and polyadenylation factor CPF specifically interacts with the pre-mRNA 3' processing signal AAUAAA

Area of Science:

• Molecular Biology
• RNA Processing
• Biochemistry

Background:

• Messenger RNA (mRNA) 3' end processing is a critical step in gene expression.
• This process involves cleavage and polyadenylation, ensuring proper mRNA function.
• The Cleavage and Polyadenylation Factor (CPF) plays a key role in these reactions.

Purpose of the Study:

• To investigate the interaction between CPF and poly(A) polymerase with short RNA substrates.
• To elucidate the specific binding mechanism of CPF to RNA.
• To identify the components of CPF involved in RNA recognition.

Main Methods:

• Gel mobility shift assays to demonstrate CPF-RNA binding.
• Competition experiments to confirm binding specificity.
• UV crosslinking to identify interacting CPF polypeptides.
• Chemical modification-exclusion experiments to map the binding site.

Main Results:

• CPF specifically binds to RNA substrates containing the AAUAAA hexamer recognition signal.
• CPF activates poly(A) polymerase activity on RNA primers with the AAUAAA signal.
• Two polypeptides (35 kDa and 160 kDa) within CPF can be crosslinked to RNA.
• CPF directly interacts with the entire AAUAAA sequence, with any base modification disrupting binding.

Conclusions:

• CPF directly binds to the AAUAAA signal on RNA, involving the entire hexamer.
• CPF's interaction with RNA is essential for activating poly(A) polymerase.
• The identified polypeptides are likely key subunits of CPF involved in RNA recognition and processing.