Virus capsids are elegant examples of biomolecular structures hierarchically assembled from a limited number of protein subunits. Here we demonstrated the bio-inspired modular construction of materials with three levels of hierarchy using virus-like particles (VLPs). The first level of hierarchy is the formation of catalytically active VLPs through directed enzyme encapsulation concurrent with VLP assembly. This was achieved by exploiting a capsid formation process involving two types of subunit proteins, coat proteins (CPs) and scaffolding proteins (SPs). Cargo proteins such as enzymes can be directed inside of VLPs through genetic fusion with SP. The second level of hierarchy is the assembly of these VLP building blocks into ordered three-dimensional arrays. This was achieved through electrostatic interaction between negatively charged VLPs and positively charged linker molecules. Ordered VLP arrays with face-centered cubic (FCC) lattices were formed at an optimal solution ionic strength at which proper balance between attractive and repulsive interaction between the building blocks was realized. We demonstrated that an array, constructed from two populations of enzyme packaged VLPs, exhibited a coupled two-step catalytic conversion for isobutanol synthesis from α-ketoisovalerate <i>via</i> isobutyraldehyde. Assembly conditions can be finely tuned by manipulating the surface charge of VLPs. This leads to implementation of the third level of hierarchy into the arrays. Two populations of VLPs were selectively assembled with spatial control over each population within the array resulting in construction of a core-shell array with an FCC structure (Fig 1). Furthermore, we recently adopted a course-grain computational method to model the higher order assembly of these VLPs. Effective feedback between computational model and experimental verification can lead to the design of hierarchically organized VLP arrays with desired functionalities in a predictable manner.

Hierarchically assembled three-dimensional array materials composed of virus-like particles (VLPs)

2019 Fall National Meeting

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