Discipline: Chemistry and Chemical Sciences
Subcategory: Biochemistry (not Cell and Molecular Biology and Genetics)
Cyrianne Keutcha - Georgia State University
Co-Author(s): Elizabeth Bennett and Dabney Dixon, Georgia State University, Atlanta, GA Michael Schmitt, Food and Drug Administration, Silver Spring, MD
Strategies to use heme as a source of iron are key to the survival and virulence of many bacteria; inhibition of iron uptake pathways may be a new strategy to prevent bacterial infection. Corynebacterium diphtheriae is a Gram-positive, pathogenic bacterium that is the causative agent of diphtheria. It utilizes heme uptake pathways to obtain required heme iron. One uptake pathway involves an ABC-type transporter encoded by the hmuTUV genes. We analyze the role of HmuT, the protein that donates heme to the ABC transporter. We hypothesize that the protein residues in the binding pocket control heme release in HmuT. Mutants studied include H136A, Y235A, Y272A, and M292A. We have used chemical and thermal denaturation to observe the effects of mutation of these key amino acids on the unfolding of the protein. We have shown that H136 and Y235 are axial ligands to the heme; M292 appears to buttress the axial tyrosine. Y272, in the heme pocket as well, also affects heme binding. Future work will involve study of the proteins as a function of pH.
Funder Acknowledgement(s): Research Corporation
Faculty Advisor: Dabney Dixon,