Molecular architecture of the multiprotein splicing factor SF3b

Area of Science:

• Molecular Biology
• Structural Biology
• Genetics

Background:

• The splicing factor SF3b is a crucial multiprotein complex.
• It plays a vital role in pre-messenger RNA splicing and intron excision.
• SF3b is integral to U2 small nuclear ribonucleoprotein (snRNP) and U11/U12 di-snRNP complexes.

Purpose of the Study:

• To determine the three-dimensional structure of the human SF3b complex.
• To identify the locations of protein domains within the complex.
• To understand SF3b's role in spliceosome function.

Main Methods:

• Single-particle electron cryomicroscopy (cryo-EM) was employed.
• The structure was determined at a resolution better than 10 angstroms.
• Computational modeling was used to fit known structural folds and protein domains.

Main Results:

• The 3D structure of the human SF3b complex was elucidated.
• The protein p14, with its RNA-recognition motif, was localized to the central cavity.
• The protein SF3b155, characterized by 22 tandem helical repeats, was found in the outer shell, enclosing p14.

Conclusions:

• The study provides the first high-resolution 3D structure of the human SF3b complex.
• Structural localization of p14 and SF3b155 offers insights into SF3b's function in pre-mRNA splicing.
• This structural information is fundamental for understanding spliceosome assembly and regulation.