Unleashing the potential of S-layer proteins for engineered living materials

The field of engineered living materials (ELMs) aims to create self-regenerative, self-assembled, and multifunctional materials that mimic natural biomaterials. Novel ELMs can be produced by engineering biomolecules that are naturally secreted and displayed on bacterial cell surfaces. Surface-layer (S-layer) proteins are a class of proteins that form a two-dimensional paracrystalline lattice on the surface of many prokaryotes. These proteins provide a secretion, surface-anchoring, and high-density display platform that can be exploited for material formation. In this review, we discuss two strategies to engineer S-layer proteins for ELMs by looking at their state of the art, analyzing their advantages and disadvantages, and discussing their challenges and opportunities.