Human CSTF2 RNA Recognition Motif Domain Binds to a U-Rich RNA Sequence through a Multistep Binding Process

Area of Science:

• Molecular Biology
• Biochemistry
• Structural Biology

Background:

• The RNA recognition motif (RRM) is a key RNA-binding domain involved in various mRNA processing events.
• The CSTF2 RRM specifically recognizes U- or G/U-rich sequences in pre-mRNA, regulating cleavage and polyadenylation.
• Alternative cleavage and polyadenylation significantly contribute to mRNA diversity, but the CSTF2 RRM binding mechanism remains unclear.

Purpose of the Study:

• To elucidate the molecular mechanism by which the CSTF2 RRM domain interacts with U-rich RNA ligands.
• To characterize the binding process and identify key structural and dynamic features involved in RNA recognition.

Main Methods:

• Nuclear Magnetic Resonance (NMR) titration and spin relaxation experiments were employed.
• Paramagnetic relaxation enhancement (PRE) measurements and rigid-body docking were utilized to complement NMR data.

Main Results:

• A multistep RNA binding process for the CSTF2 RRM was revealed.
• Significant differences in picosecond-to-nanosecond (ps-ns) timescale dynamics were observed.
• Potential structural alterations, particularly in the C-terminal α-helix, were identified during ligand binding.

Conclusions:

• The study provides novel insights into the dynamic binding of the CSTF2 RRM to U-rich RNA.
• Understanding these interactions is crucial for comprehending the regulation of pre-mRNA cleavage and polyadenylation.
• This work lays the foundation for further structural and mechanistic studies of RRM-RNA interactions.