Olive J. Njuma

Olive joined the Goodwin laboratory in the Summer of 2012.  She came to us by something of a circuitous route, having first worked in the laboratory of an Organic Division faculty member. When that individual took a position at another university, Olive decided to remain at Auburn and switch her emphasis to biochemistry.  We are delighted to have her. Olive has focused her efforts upon understanding the mechanisms by which the catalase activity of KatG is inactivated, and how peroxidatic electron donors prevent this process, and therefore, stimulate catalase activity.  These phenomena are particularly prominent at lower pH (e.g., 5.0), and this is especially important because host responses to pathogen attack often involve production of copious quantities of hydrogen peroxide and are carried out under acidic pH conditions. Stimulation of KatG catalase activity by peroxidatic electron donors may have a role in the virulence of several pathogens which rely on KatG as an antioxidant defensive mechanism.  Perhaps, no pathogen in this group is more prominent than Mycobacterium tuberculosis.  KatG is the only enzyme this organism produces that has catalase activity, and it is known that the greatest abundance of M. tuberculosis cells in infected human hosts are found inside neutrophils. Olive has applied site-directed mutagenesis, steady-state kinetic, as well as transient-state kinetic methodology to investigate KatG catalase inactivation and rescue by peroxidatic electron donors. Indeed, she is the first from our laboratory to make extensive use of rapid-freeze-quench EPR to investigate KatG protein-based radicals. In this effort, we have collaborated with the laboratory of Dr. Aimin Liu now at University of Texas at San Antonio, most especially Ian Davis, a graduate student in the group. Olive also recently traveled to the National High Magnetic Field Laboratory in Tallahassee, FL to perform high frequency EPR measurements on some of her freeze-quenched samples. On June 2, 2016, Olive successfully defended her dissertation Resolving the Paradoxical Nature of a Bifunctional Enzyme: Pathways and Regulation of Intramolecular Electron Transfer in KatG.  Olive engaged in postdoctoral research in the laboratory of Professor Fred Guengerich at the Vanderbilt University School of Medicine before moving on to California, first to Molecular Assemblies, Inc. She is now in Torrance, CA, working with PolyPeptide Group as a Senior Analytical Development Scientist.

Publications and Abstracts
Njuma, O. J., Davis, I., Ndontsa, E. N., Krewall, J. R., Liu, A., and Goodwin, D. C. 2017. Mutual synergy between catalase and peroxidase activities of the bifunctional enzyme KatG is facilitated by electron-hole hopping within the enzyme. J. Biol. Chem. 292, 18408 - 18421.

Krewall, J. R., Njuma, O. J., and Goodwin, D. C. 2017. Role reversal between peroxidase reaction intermediates generates the distinct catalase mechanism of catalase-peroxidase. 46th Annual Southeast Magnetic Resonance Conference, Tallahassee, FL, (10/29/17).

Xu, H., Krewall, J. R., Njuma, O. J., and Goodwin, D. C. 2017. How an arginine switch preserves the catalase activity of KatG: Strategic use of an active-site tryptophan for off-pathway electron transfer. 46th Annual Southeast Magnetic Resonance Conference, Tallahassee, FL, (10/29/17).

Xu, H., Krewall, J. R., Njuma, O. J., Davis, I., Liu, A., and Goodwin, D. C. 2017. Using an arginine switch and an active site tryptophan to direct off-pathway electron transfer: Maximizing catalase activity from a peroxidase scaffold. Gordon Research Conference: Enzymes, Coenzymes, and Metabolic Pathways, Waterville Valley, NH, (7/16/17 – 7/21/17).

Krewall, J. R., Xu, H., Njuma, O. J., and Goodwin, D. C. 2017. Directing off-pathway protein oxidation to preserve enzyme activity: At last, a role for the proximal tryptophan of KatG. 8th Annual Southeast Enzyme Conference, Atlanta, GA, (04/08/17).

Xu, H., Krewall, J. R., Njuma, O. J., and Goodwin, D. C. 2017. How an arginine switch preserves the catalase activity of KatG: Strategic use of an active-site tryptophan for off-pathway electron transfer. 8th Annual Southeast Enzyme Conference, Atlanta, GA, (04/08/17).   

Kudalkar, S. N., Njuma, O. J., Li, Y., Muldowney, M., Fuanta, N. R., and Goodwin, D. C. 2015.  A role for catalase-peroxidase large loop 2 revealed by deletion mutagenesis: Control of active site water and ferric enzyme reactivity. Biochemistry 54, 1648 - 1662.

Njuma, O. J., Davis, I., Ndontsa, E. N., Liu, A., and Goodwin, D. C. 2015. Proximal tryptophan and arginine switch participation in catalase-peroxidase inactivation. Gordon Research Conference: Enzymes, Coenzymes, and Metabolic Pathways, Waterville Valley, NH (7/13/15 -7/14/15)

Njuma, O. J., Davis, I., Ndontsa, E. N., Liu, A., and Goodwin, D. C. 2015. Participation of the proximal tryptophan as a potential conduit for catalase-peroxidase inactivation. 6th Annual Southeast Enzymes Conference, Georgia State University, Atlanta, GA (4/11/15).

Njuma, O. J., Ndontsa, E. N., and Goodwin, D.C. 2015. Electron donors to the  rescue: The proximal Trp as a potential conduit for catalase-peroxidase  inactivation. Departmental Seminar, Department of Chemistry, University of Buea, Cameroon. (4/1/15).

McCurdy, E., Barr, L., Njuma, O.J., Ndontsa, E. N., and Goodwin, D.C. 2015. Evaluating the novel role of Trp 438 in active turnover of Mycobacterium tuberculosis catalase-peroxidase. Auburn University J. of Undergrad. Scholarship. 4, 27 - 32.

Njuma, O. J., Ndontsa, E. N., and Goodwin D. C. 2014. Catalase in peroxidase clothing: Interdependent cooperation of two cofactors in the catalytic versatility of KatG. Arch. Biochem. Biophys. 544, 27 – 39.

Njuma, O. J., Ndontsa, E.N., and Goodwin, D.C. 2014. pH-dependent catalase stimulation of catalase-peroxidases by peroxidatic electron donors. 43rd Southeastern Magnetic Resonance Conference (SEMRC), Tuscaloosa, AL. (10/25/14)
Njuma, O. J., Ndontsa, E.N., and Goodwin, D.C. 2014. Evaluating an atypical mechanism of H2O2 decomposition by catalase-peroxidases. The Southeast Regional Meeting of the American Chemical Society (SERMACS), Nashville, TN. (10/18/14)

Njuma, O. J., Ndontsa, E. D., and Goodwin, D. C. 2014. Evaluating the role of peroxidatic reducing substrates in an unusual catalase activity of catalase-peroxidases. 2014 Symposium, The Protein Society, San Diego, CA. (7/27/14)

Njuma, O. J., Ndontsa, E. D., and Goodwin, D. C. 2014. Synergistic effect of peroxidatic electron donors on the catalase activity of Catalase-Peroxidase. 5th Annual Southeast Enzymes Conference, Georgia State University, Atlanta, GA. (4/5/14)

Njuma, O. J., Ndontsa, E. N. and Goodwin, D. C. 2014. Evaluating the role of electron donors in a novel mechanism of H2O2 decomposition by Catalase-Peroxidase. 91st  Alabama Academy of Science Meeting (AAS), Auburn University, AL (3/13/14) (Won first prize for poster presentation).

McCurdy, E., Njuma, O. J., Ndontsa, E., and Goodwin, D. 2014. W438 and the Diminished Necessity for Peroxidatic Rescue of KatG Catalatic Turnover. 34th Annual Undergraduate Research Conference, University of Memphis, Memphis, TN.

 

McCurdy, E., Njuma, O. J., Ndontsa, E. N., and Goodwin, D. C. 2013. An Investigation of W438 as a Potential Route for Off-Pathway Electron Transfer and Its Relationship to the Bifunctional Activity of Catalase-Peroxidase.  Southeast Regional Meeting of the American Chemical Society (SERMACS), Atlanta, GA. (Won first prize for undergraduate poster session).

Njuma, O. J., Ndontsa, E. N., and Goodwin, D. C. 2013. Rescue of catalase-inactive intermediates of KatG by peroxidatic electron donors. Southeast Regional Meeting of the American Chemical Society (SERMACS), Atlanta, GA

 

Njuma, O. J., Ndontsa, E. N and Goodwin, D.C. 2013. KatG: Improvisation of novel peroxide decomposition mechanisms. 99th Annual Southeastern Branch of  American Society of  Microbiology Meeting (SEBASM), Auburn University, AL.

Njuma, O. J., Ndontsa, E.N., and Goodwin, D.C. 2013. KatG: Bacterial improvisation of novel peroxide decomposition mechanisms. Three minute thesis, Auburn University, Auburn, AL.

Njuma, O. J., Ndontsa, E. N., and Goodwin, D. C. 2013. Electron donors to the rescue: Evaluating a novel mechanism of hydrogen peroxide decomposition by catalase-peroxidases. National Meeting of the National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCCHE), Indianapolis, IN.

 

Njuma, O. J., Ndontsa, E. N., and Goodwin, D. C. 2013. Surprising role of peroxidatic electron donors in the catalase activity of catalase-peroxidase. Diversity Awareness Symposium, Tuscaloosa, AL.  (Award-winning poster)

 

Njuma, O. J., Ndontsa, E. N., and Goodwin, D. C. 2013. Surprising role of peroxidatic electron donors in the catalase activity of Catalase-Peroxidase. Fourth Southeast Enzymes Conference, Atlanta, GA.