Interaction proteomics analysis to provide insight into TFAMoplex-mediated transfection.

In an earlier investigation, our group introduced the TFAMoplex, a transfection agent based on the mitochondrial transcription factor A (TFAM) protein, which complexes DNA into nanoparticles. The original TFAMoplex further contained a bacterial phospholipase to achieve endosomal escape, and the vaccinia-related kinase 1 (VRK1), which significantly boosted the transfection efficiency of the system by an unknown mechanism. This study aims at replacing VRK1 within the TFAMoplex with dynein light chain proteins, specifically RP3, to directly tether the complexes to the dynein motor complex for enhanced cytosolic transport. To confirm the interaction between the dynein complex and the resulting fusion protein, we examined the binding kinetics of TFAM-RP3 to the dynein intermediate chains 1 and 2. Furthermore, we established a proteomics-based assay to compare cytosolic protein interactions of different TFAMoplex variants, including the RP3-modified version and the original VRK1-containing system. In the group of the VRK1-containing TFAMoplex, significant shifts of protein interactors were observed, especially for nucleolar proteins. Leveraging this knowledge, we incorporated one of these nuclear proteins, leucine-rich repeat-containing protein 59 (LRRC59), into the TFAMoplex, resulting in a significant improvement of transfection properties compared to the RP3-modified system and comparable levels versus the original, VRK1-containing version. This study not only advances our comprehension of the TFAMoplex system but also offers broader insights into the potential of protein engineering for designing effective gene delivery systems.