The spliceosomal proteins PPIH and PRPF4 exhibit bi-partite binding

Area of Science:

• Molecular Biology
• RNA Biology
• Protein Interactions

Background:

• Pre-mRNA splicing is essential for gene expression, catalyzed by the spliceosome.
• Peptidyl-prolyl isomerase H (PPIH) and pre-mRNA processing factor 4 (PRPF4) are core spliceosome components in higher organisms.
• PPIH and PRPF4 integrate into the spliceosome as part of the tri-snRNP complex.

Purpose of the Study:

• To understand the protein interactions governing PPIH and PRPF4 function within the spliceosome.
• To characterize the interaction interface between PPIH and PRPF4.
• To investigate how this interaction influences spliceosomal activity.

Main Methods:

• Expression and purification of soluble PPIH and PRPF4 proteins.
• Formation and analysis of the PPIH-PRPF4 complex.
• Mutational analysis to identify critical binding sites and their disruption.

Main Results:

• Two distinct interaction sites were identified between PPIH and the intrinsically disordered N-terminus of PRPF4.
• The N-terminus of PRPF4 remains disordered upon PPIH binding.
• Disruption of both identified binding sites was required to dissociate the PPIH-PRPF4 complex.

Conclusions:

• The PPIH-PRPF4 interaction is bipartite, involving two distinct binding sites.
• This interaction may play a regulatory role in spliceosome function.
• Further studies are needed to elucidate the functional consequences of this bipartite interaction.