Vanderbilt engineers’ innovative research directly monitors cellulose production from individual synthase enzymes

Vanderbilt researchers have uncovered conditions needed to produce cellulose at the single molecule level that could one day aid in the dismantling of bacterial defenses as well as potentially lead to the engineering of more efficient and cost-effective biofuel feedstock sources.

The findings were published in the scientific journal PNAS. The researchers used optical tweezers and fluorescence to observe and measure the activity of a single bacterial cellulose synthase (BcsAB) enzyme at a time to uncover how it works. BcsAB is the culprit for production of cellulose, a main component of bacterial biofilms. Researchers harbored the enzyme in a surface-bound nanodisc and grabbed the growing strand with a bead held with a focused beam of light. They showed that cellulose growth rates are a strong function of temperature and produce strands that are mechanically tough, riddled with microstructure revealing repeat folding and bonding back on itself.

Researchers said the work is just the fourth polymer synthase to be characterized at the single molecule level. Others include machines that make DNA, RNA and proteins.

“These findings will help usher the next generation of antimicrobial treatments, targeting biofilm structure and formation to dismantle bacterial defenses,” said Mark Hilton, lead author of the paper and program manager of entrepreneurship at The Wond’ry, Vanderbilt’s Innovation Center. “Some common infections that originate from these resistant bacteria are endocarditis in the heart or cystic fibrosis in the lungs. Approximately 65% of hospital-borne infections and 100,000 deaths annually in the U.S. are attributed to this class of bacteria. Dismantling the bacterial biofilm is a crucial step to eliminating these bacteria.”

In the case of biofuel feedstocks, researchers said they are typically derived from plant material with cellulose, the most abundant biopolymer on earth, being a top biofuel precursor in the industry.

“Much effort in the biofuel industry is devoted to isolating cellulose from plant material,” added Hilton. “The knowledge from our study on how cellulose is made could potentially lead to the engineering of more efficient and cost-effective biofuel feedstock sources, whether plants or bacteria.”

Matthew Lang, professor of chemical and biomolecular engineering at Vanderbilt and a co-author on the paper, said the cellulose research is at the basic stage but he is optimistic it will lead to more breakthroughs.

“It can be many years before this propagates into something, but you have to build it up now,” said Lang, who has a laboratory in Vanderbilt’s School of Engineering. “You have to be doing the basic research now in order to ultimately get there. And if you do get there, the impact can be huge.”

This work, a collaboration with the Zimmer Lab at the University of Virginia, is supported by an NIH grant (5R01GM101001), a Department of Energy bioimaging award (Office of Science DE-SC0019313), an NSF Division of Chemical, Bioengineering, Environmental, and Transport Systems (NSF CBET) award (1604421), and an NSF Division of Molecular and Cellular Biosciences (NSF MCB) award (1330792).

Contact: Lucas Johnson, 615-343-0137