Congratulations to my Rutgers University PhD student Antonio De Chellis who led the discovery of novel supercharged enzymes designed for more efficient conversion of cellulosic biomass to fermentable sugars. My former PhD student (Bhargava Nemmaru, PhD) had initiated this exciting project in my lab along with collaborator Deanne Sammond. Also, special thanks to all graduate (Jenna Douglass, Nivedita Patil) and undergraduate (Olivia Reste) researchers that contributed to this work.
This study demonstrates the first successful implementation of an enzyme supercharging design strategy to increase cellulase hydrolysis activity towards lignocellulosic biomass. This work was published in an American Chemical Society journal called ‘Sustainable Chemistry and Engineering’ earlier this month. Check out link for details (https://lnkd.in/eA2-D5s3).
Briefly, protein surface ‘supercharging’ has been hypothesized to reduce non-productive binding to biomass to improve biodegradability, but with limited demonstrated success to date. Here, we computationally designed and characterized a library of supercharged cellulase catalytic domains and associated carbohydrate binding module originally belonging to an industrially relevant thermophilic microbe (Thermobifida fusca). Surprisingly, mutations on the binding domain alone resulted in improved activity on cellulosic biomass, with top-performing supercharged mutants exhibiting between 2- and 5-fold increase in activity, compared to native enzyme, on both cellulosic biomass enriched in lignin (i.e., corn stover) as well as purified crystalline and amorphous cellulose. Furthermore, we were able to fine tune enzyme net charge (i.e., binding affinity) for targeting distinct substrates to identify the ‘Sabatier Optimum’ for the heterogenous reaction. Lastly, several supercharged cellulase designs exhibited upto 10 °C increase in optimal hydrolysis temperature. We now have a patent filed for several supercharged enzyme designs discovered in this study.
This research was made possible primarily due to financial support from the National Science Foundation (NSF), NSF Career Award, Rutgers School of Engineering, and Rutgers University Aresty Undergraduate Research Program. Also, U.S. Department of Energy (DOE) Joint Genome Institute (DOE-JGI) supported this work through the Community Science Program Gene Synthesis Award. Lastly, Antonio was partially supported by the Rutgers-NIH Biotechnology Training Program fellowship.
Special thanks to Rebecca Ong and Bruce E. Dale for providing access to AFEX pretreated biomass used in this work.
Original preprint for this paper is available on the BioRxiv as well.
https://lnkd.in/e8-Ghh6r