A UHM-ULM interface with unusual structural features contributes to U2AF2 and SF3B1 association for pre-mRNA splicing

Area of Science:

• Molecular Biology
• Structural Biology
• RNA Biology

Background:

• Spliceosome assembly involves sequential recognition of the 3' splice site by U2AF2 complexes.
• The U2AF2-SF1 interaction is characterized, but the U2AF2-SF3B1 interface structure and function in pre-mRNA splicing remain unknown.

Purpose of the Study:

• To determine the crystal structure of the U2AF2 UHM bound to a SF3B1 ULM.
• To investigate the functional significance of the U2AF2-SF3B1 interface in pre-mRNA splicing.

Main Methods:

• Crystal structure determination at 1.8-Å resolution.
• Analysis of binding affinities and coimmunoprecipitation assays.
• Assessment of splicing changes upon disruption of the U2AF2-SF3B1 interface.

Main Results:

• A unique U2AF2 UHM-SF3B1 ULM structure was elucidated, revealing a distinct binding trajectory.
• The U2AF2-SF3B1 interaction exhibits significant binding affinity and is crucial for coimmunoprecipitation.
• Disruption of this interface alters splicing of human transcripts, with distinct splice site usage compared to U2AF2-SF1.

Conclusions:

• The U2AF2-SF3B1 complex possesses distinct structural and functional properties compared to U2AF2-SF1.
• This interaction plays a critical role in regulating splice site selection during pre-mRNA splicing.