Two WVU Health Sciences researchers recently had their work published online in Nature Microbiology, a scientific journal that publishes exceptional research from across the field of microbiology. The manuscript is entitled “Spirochaete flagella hook proteins self-catalyse a lysinoalanine covalent crosslink for motility.”

Nyles Charon, Ph.D., professor in the Department of Microbiology, Immunology and Cell Biology

Front row, left to right: Nyles Charon, Milinda James, Michael Miller. Back row: Patrick Callery, Andrew Cockburn.

and Michael Miller, Ph.D., professor in the Department of Biochemistry, initiated the research and collaborated with a nationwide team of investigators to identify the self-catalytic nature of FlgE crosslinking for protein engineering, and its sensitivity to chemical inhibitors.

FlgE is a protein that forms a critical element of the spirochete flagella referred to as the hook. If the hook is incapacitated, the bacteria cannot move and is not infective. They focused their research on Treponema denticola, a bacterium that is part of the human oral microbiome and is associated with periodontal disease. Besides characterizing the covalent cross-link that links FlgE proteins together, they engineered mutants that were not only defective in forming the cross-link, but lacked motility. The

Cryoelectron microscopy colorized image of the oral spirochete Treponema denticola. The cells were photographed on a grid containing holes.     

lysinoalanine cross-link they identified is highly unusual in all living cells, but the FlgE’s capacity to self-catalyze covalent cross-links is remarkable, as few proteins in nature are able to carry out this type of reaction. 

This particular research is relevant to paving the way for the development of new drugs that inhibit cross-linking and treat spirochetal diseases, including Lyme disease, syphilis, and periodontal disease. Furthermore, the ability to exploit the self-catalytic reaction may be important in engineering cross-links in other proteins besides FlgE, as for example, for the delivery of drugs for cancer treatment. Their research was supported by a grant from the National Institute of Dental and Craniofacial Research, one of the National Institutes of Health in the U.S. Department of Health and Human Services.