Date of Award


Degree Type


Degree Name

Master of Science (MS)



First Advisor

Dr. Dabney Dixon

Second Advisor

Dr. Giovanni Gadda

Third Advisor

Dr. Donald Hamelberg


Gram-positive pathogenic bacteria utilize cell-surface anchored proteins to bind and transport heme into the cell. These bacteria acquire iron from host proteins containing heme e.g., hemoglobin. Proteins like HmuT from Corynebacterium diphtheriae bind and help transport heme into the cell. Residues His136 and Tyr235 are utilized as the axial ligands, with a conserved Arg237 residue acting as the hydrogen bonding partner to the axial Tyr235. Similarly, Streptococcus pyogenes utilizes the cell anchored protein Shr to transfer heme into the cell. Shr-NEAT2 is hexacoordinated by two axial methionines and is prone to autoreduction where lysines are the most likely source of electrons. Lastly, PefR of Group A Streptococcus is a DNA transcription factor which regulates protein expression. Preliminary studies indicate a cysteine may coordinate the heme. A combination of UV-visible, resonance Raman, and magnetic circular dichroism spectroscopies shows these proteins play a crucial role heme transport and regulation.