Compartmentalization is a critical component of cellular function, enabling a multitude of biochemical reactions to occur at specific location in the cell at specific times. Reproducing such performance with one or more biological and chemical catalysts in the lab and in industry offers tremendous opportunities for future developments of green and sustainable chemical processes. The proposed project draws inspiration from nature by exploring bacterial "capsules" as containers for the orderly immobilization of catalysts. The capsules are nanometer-scale, hollow spheres with protein shells that assemble spontaneously. Protein engineering strategies will be explored to tailor these nanostructures to the specific reaction sequences of interest. The goals are to improve the selective passage of raw materials through the shell, and to reproducibly "decorate" the interior side of the shell with specific reaction catalysts. In combination, these efforts will produce engineered nano-scale reactor vessels that can be designed to perform a variety of industrially interesting reaction sequences. There will also be STEM career development efforts that will involve students from K-12 through college age. These include Science Days at an elementary school, protein modeling competitions for local high school students, undergraduate research experiences, and protein design and 3D printing activities at the Annual Atlanta Science Festival.
The project will explore the impact of catalytic performance of (bio) catalysts upon encapsulation in and controlled surface-immobilization on protein-based encapsulin nanocompartments. Protein engineering strategies ranging from random mutagenesis and incremental truncation to protein design will be employed to remodel nanocompartments for enhanced substrate and product permeability and to create new opportunities for functional diversification via artificial affinity sites on the encapsulin surfaces. Beyond single particles, the assembly of nanocompartments into multi-dimensional nanoreactor assemblies for high-density biocatalyst systems will be explored. Using a combination of biophysical methods, as well as biocatalytic and biosensory systems, the impact of these engineering efforts on the structure of nanocompartments themselves and the function of the associated catalysts will be assessed. By integrating design parameters into this system that offer the potential for high enantioselectivity and reduced separation costs, this technology would have significant implications for therapeutic drug development.
