Biochemistry: Assistant Professor of Biochemistry
Metallocofactors in enzymatic reactions
Allison Saunders joined Lycoming College after teaching biochemistry at Mansfield University. Saunders received her doctorate from Penn State University where her research focused on isolating and characterizing enzymes that use iron-sulfur clusters as cofactors. After graduating, Saunders continued at Penn State University as a post-doctoral fellow studying iron-sulfur cluster-containing enzymes from photosynthetic bacteria. At Lycoming she teaches biochemistry and general chemistry. While she has a broad interest in the sciences, there is nothing more exciting to Saunders than chemistry that happens inside a living cell.
At Lycoming, Saunders is continuing research on enzymes that contain iron-sulfur (Fe/S) clusters, specifically those in the radical S-adenosylmethionine (SAM) superfamily. These oxygen-sensitive enzymes use their Fe/S cluster(s) to catalyze the reductive cleavage of SAM to methionine and a 5’-deoxyadenosyl radical. This radical then initiates catalysis by abstracting a hydrogen atom from a bound substrate or a protein. The radical SAM enzymes are involved in a variety of interesting transformations including sulfur insertion and thioether bond formation, methylation and methylthiolation, cyclopropanation, and many more. These enzymes are present in all domains and kingdoms of life, yet they are abundant in eubacteria and archaea, and have critical roles in the metabolism of obligate or facultative anaerobes. Many are found in human gut microbiota, which has been shown to be a major factor in human diseases, such as obesity and inflammatory diseases. The goals of her research are to identify novel radical SAM enzymes in metabolic pathways of human gut microbiota and characterize them by overproducing and purifying proteins for further biochemical investigations.
Esakova, O. A., Silakov, A., Grove, T. L., Saunders, A. H., McLaughlin, M. L., Yennawar, N. H., and Booker, S. J. (2016) Structure of Quinolinate Synthase from Pyrococcus horikoshii in the Presence of Its Product, Quinolinic Acid, J. Am. Chem. Soc., 138, 7224-7227.
Saunders, A. H., Golbeck, J. H., and Bryant, D. A. (2013) Characterization of BciB: a ferredoxin-dependent 8-vinyl-protochlorophyllide reductase from the green sulfur bacterium Chloroherpeton thalassium, Biochemistry, 52, 8442-8451.
Saunders, A. H., Griffiths, A. E., Tu, L., Lee, K. H., Cicchillo, R. M., Stromberg, J. A., Krebs, C., and Booker, S. J. (2008) Characterization of quinolinate synthases from Escherichia coli, Mycobacterium tuberculosis, and Pyrococcus horikoshii indicates that [4Fe-4S] clusters are common cofactors throughout this class of enzymes, Biochemistry, 47, 10999-11012.
Saunders, A. H.
, and Booker, S. J. (2008) Regulation of the activity of Escherichia coli
quinolinate synthase by reversible disulfide-bond formation, Biochemistry
, 47, 8467-8469.