Bacterial Surface-Assembled Chitinosome for Dismantling Chitin into N-Acetyl Glucosamine

The construction of an efficient multienzyme catalyst for dismantling recalcitrant polymers into high-value-added chemicals is appealing in sustainable biomanufacturing. Colocalization of cascade enzymes has been broadly adopted by natural and synthetic multienzyme systems for chemical synthesis, while there has been rare research on the decomposition of polymeric substrates. In this study, we constructed an E. coli surface-assembly (ESA) system to colocalize a synthetic chitinosome composed of two chitin hydrolases, BpChiA and BlNagZ, via the SpyCatcher/SpyTag (SpyC/SpyT) conjugation. In the ESA–chitinosome complexes, the loading efficiency and specific activity of enzymes were improved by tuning the copies of SpyC and the linker lengths between the SpyT and enzymes, respectively. The ratio of BpChiA and BlNagZ was also optimized. The ESA–chitinosome complexes exhibited higher productivity of N-acetyl glucosamine than the mixture of separately assembled enzymes on cell surfaces. This work demonstrates that the enzyme colocalization and the formation of the ternary ESA–chitinosome–chitin complexes are critical for the catalytic synergism of cascade enzymes, providing new insights into the decomposition of recalcitrant polymeric substrates.