Mechanistic Enzymology
An enzyme is a substance that acts as a catalyst in living organisms, regulating the rate at which chemical reactions proceed without being altered in the process itself [3]. Enzymes essentially lie at the heart of biochemistry, accelerating chemical reactions to an astounding extent with extraordinary specificity. Enormous progress in understanding the chemical basis of enzymatic processes and the basic mechanisms behind the enhancement of reaction rates has taken place in the past decades [2]. Enzymology is the branch of biochemistry aiming to understand how enzymes work using the relationship between their structure and function. So, it is a multidisciplinary research field and integrates areas of biochemistry, microbiology, molecular biology, molecular genetics, and biophysics [1]. It is exactly this field in which Dr. Kayunta Johnson-Winters, associate professor of chemistry and biochemistry at the University of Texas at Arlington, conducts her research as a mechanistic enzymologist.
The F20 Cofactor
Dr. Johnson-Winters specialises in the research of F420-dependent enzymes, found in mycobacterium tuberculosis, a special class of pathogenic bacteria that causes tuberculosis [6]. F420 is a cofactor. In biochemistry, a cofactor is a non-protein chemical that assists with a biological chemical reaction. Cofactors may be metal ions, organic compounds, or other chemicals that have helpful properties that are not usually found in amino acids. Some cofactors can be made inside the body, such as ATP, while others must be consumed in food [4]. Mycobacterium tuberculosis bacteria rely heavily on the F20 cofactor for their redox reactions. In these bacteria F420 has been shown to enhance persistence and to activate some new clinical antitubercular drugs (class of drugs used to treat TB) [5].
Recent studies have shown that the cofactor F420 is critical for resistance of mycobacteria to antimicrobial compounds. Strains of bacteria that are unable to synthesise or reduce this cofactor are usually extremely susceptible to most antimicrobial compounds. This suggests that mycobacteria employ this cofactor in their detoxification process. It is also possible that F420 enhances the capacity of mycobacteria to resist antimicrobial agents through maintaining cell wall structure and generating antioxidants [7].
Diversity in STEM and the Importance of Inclusion: A Conversation with Dr. Kayunta Johnson-Winters
By almost every measure, the U.S. STEM ecosystem is inequitable. Even while the share of science and engineering bachelor’s and doctorate degrees awarded to Hispanic or Latino, Black and African American, and American Indian and Alaska Native graduates has increased over the past two decades, they are still underrepresented among science and engineering degree recipients relative to their representation in the overall population [8].
Scientific progress depends on people learning about new things and studying existing things in new ways. and having racially and ethnically diverse people included means bringing different lenses, different experiences, different questions, different passions – and getting better results. By being more inclusive, the likelihood of scientific success is higher, promoting economic growth and competitiveness. More importantly, access to STEM education is a social justice issue, and we have an opportunity and a responsibility to alleviate disparities and contribute to the acceleration of social equality.
However, striving for diversity and inclusion may also cause harm to those advocating for it. As one of the few staff members of colour at her university, Dr. Johnson-Winters remains candid about the difficulties she faces as a consequence. While she acknowledges the importance of representation, she highlights how it can be tough to really give time to her research – and her students – when she’s busy with her responsibilities towards different committees and societies targeting the issue of diversity. In our podcast, she thus iterates how she’s learned to say “no” to some of her superiors – in a manner that is firm, yet doesn’t alienate her from future opportunities. Knowing that this isn’t just a university-specific problem, Dr. Johnson-Winters advocates for a paradigm shift in foundational policies – especially those that were created to subserve and benefit only a particular class of people.
Learn More
If you’d like to hear more about the fascinating science of enzymology and the importance of diversity in chemistry, visit us on Spotify to listen to our ChemTalk podcast with Dr. Kayunta Johnson-Winters, associate professor of chemistry and biochemistry at the University of Texas, Arlington, to learn more about how she stumbled onto the F420 cofactor, why she chose academia over industry, and to learn about the ‘chemistry of life’.
Find the ChemTalk podcast here.
Works Cited
[1] S. Mitic, S. de Vries, in Comprehensive Biophysics, 2012.
[2] Herschlag, D., & Natarajan, A. (2013). Fundamental challenges in mechanistic enzymology: progress toward understanding the rate enhancements of enzymes. Biochemistry, 52(12), 2050–2067. https://doi.org/10.1021/bi4000113
[3] Britannica, T. Editors of Encyclopaedia (2022, August 19). enzyme. Encyclopedia Britannica. https://www.britannica.com/science/enzyme
[4] BD Editors. “Cofactors”. Biology Dictionary. April 18, 2017.
[5] Bashiri, G., Antoney, J., Jirgis, E.N.M. et al. A revised biosynthetic pathway for the cofactor F420 in prokaryotes. Nat Commun 10, 1558 (2019). https://doi.org/10.1038/s41467-019-09534-x
[6] Johnson-Winters, Kayunta. Personal Interview. Conducted by Olivia Lambertson. 22 November 2022.
[7] Jirapanjawat, T., Ney, B., Taylor, M. C., Warden, A. C., Afroze, S., Russell, R. J., Lee, B. M., Jackson, C. J., Oakeshott, J. G., Pandey, G., & Greening, C. (2016). The Redox Cofactor F420 Protects Mycobacteria from Diverse Antimicrobial Compounds and Mediates a Reductive Detoxification System. Applied and environmental microbiology, 82(23), 6810–6818. https://doi.org/10.1128/AEM.02500-16
[8] Xiao-Wei Wang, Natalie Lake. “Why Diversity in STEM Matters”. Packard Foundation. November 23, 2021.