Molecular architecture of the human Prp19/CDC5L complex

Area of Science:

• Molecular Biology
• Biochemistry
• Cell Biology

Background:

• The Prp19 complex is essential for the catalytic activation of the spliceosome.
• It forms a major component of the spliceosome's catalytic core ribonucleoprotein particle (RNP).
• Understanding the spatial organization of the human Prp19 (hPrp19)/CDC5L complex is key to understanding spliceosome function.

Purpose of the Study:

• To investigate the molecular organization and protein-protein interactions within the native human Prp19 (hPrp19)/CDC5L complex.
• To elucidate the structural components and interactions critical for the spliceosome's catalytic core.

Main Methods:

• Purification of native hPrp19/CDC5L complexes from HeLa cells.
• Stoichiometric analysis, salt treatment, and protein-protein interaction studies.
• Limited proteolysis and electron microscopy for structural determination.

Main Results:

• The hPrp19/CDC5L complex contains four copies of hPrp19, similar to yeast NTC.
• A stable core was identified, comprising CDC5L, hPrp19, PRL1, and SPF27.
• SPF27 interacts with all core components, and new interactions were discovered. A protease-resistant core structure was defined, and electron microscopy showed an elongated, asymmetric shape (~20 nm).

Conclusions:

• The study elucidates the molecular organization of the hPrp19/CDC5L complex.
• It provides insights into the protein-protein interactions within the catalytically active spliceosome core.
• Findings contribute to understanding spliceosome assembly and function.