Probing subunit interactions of E2 protein scaffold for controlled release applications

Biogenic systems such as virus and heat shock proteins can self- assemble and can be modified with different functionalities for nanotechnology applications. The 60-meric dihydrolipoyl acyltransferase (E2) core of pyruvate dehydorogenase from Bacillus stearothermophilus forms a dodecahedral complex with hollow inner cavity that serves as a promising platform for drug encapsulation. In our studies, a truncated E2 core was modified at residues 355 and 356. These positions were identified via visual inspection by examining interactions between different residues at subunit interfaces. Two mutants, namely W355A and F356H, were successfully constructed by replacing tryptophan and phenylalanine residues with alanine and histidine, respectively. The molecular weight of the purified mutant proteins as determined by SDS- PAGE and MALDI- TOF was 28kDA which was comparable to that of wild- type E2. The mutants assembled correctly and the diameter was determined to be 24.01 and 26.56 nm using dynamic light scattering technique. PDI of 0.232 and 0.243 also indicated that these purified proteins were monodisperse. The correct assembly of the scaffolds with non- native functionalities allows potential study into elucidation of self-assembly mechanism and thus provides important insights into viable strategies for applications in controlled therapeutic delivery.Bachelor of Engineering (Chemical and Biomolecular Engineering