SLIRP stabilizes LRPPRC via an RRM-PPR protein interface

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Leucine-rich PPR-motif containing protein (LRPPRC) is crucial for mitochondrial gene expression.
• Mutations in LRPPRC cause severe infantile mitochondrial neurodegeneration.
• LRPPRC is a pentatricopeptide repeat (PPR) protein family member known for RNA binding.

Purpose of the Study:

• To investigate the RNA binding capabilities of LRPPRC and SLIRP.
• To elucidate the structural basis of the LRPPRC-SLIRP complex formation.
• To understand the functional implications of protein-protein interactions in the complex.

Main Methods:

• In vitro RNA binding assays.
• Protein complex formation analysis.
• Structural analysis of protein-protein interactions.

Main Results:

• LRPPRC exhibits strong and broad in vitro RNA binding.
• SLIRP shows weak RNA association.
• The LRPPRC-SLIRP complex is a heterodimer stabilized by specific amino acid interactions.
• Residues predicted to bind RNA in both proteins are involved in protein-protein binding.

Conclusions:

• The LRPPRC-SLIRP complex formation is primarily driven by protein-protein interactions, not RNA binding.
• Specific residues within LRPPRC's PPR motifs and SLIRP's RRM domain facilitate complex stability.
• This interaction mechanism is critical for LRPPRC's function in mitochondrial gene regulation.