Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis, one of the top ten causes of death worldwide. One of the genes upregulated in Mtb during macrophage infection is rv2633c, but the structure and function of its gene product remain unknown. Preliminary research has indicated that Rv2633c is a hemerythrin-like protein that exhibits catalase activity and binds two iron atoms using an HHE domain. Additionally, Rv2633c appears to exist as a dimer. The purpose of this project is to identify specific residues outside of the HHE domain that contribute to the protein's iron-binding ability and/or catalase activity, and to determine whether residues on the C terminus are required for dimerization. Conserved residues D37, E42, and E95 were selected due to their proximity in the amino acid sequence to the HHE domain. Each residue was mutated to alanine using site-directed mutagenesis and the mutations were confirmed using Sanger sequencing. The E95A mutant and the C-terminal truncation mutant were expressed in Escherichia coli using the T7 expression system and purified using affinity chromatography. While wild-type Rv2633c eluted as a soluble protein, the C-terminal truncation mutant was not soluble, indicating that the C terminus may be required for Rv2633c folding. The E95A mutant eluted as a soluble protein, but may have lower iron content than wild-type Rv2633c, indicating that this glutamic acid residue could contribute to iron-binding, despite being outside the HHE domain.
Bachelor of Science (B.S.)
College of Medicine
Burnett School of Biomedical Sciences
Orlando (Main) Campus
Rosch, Kelly M., "The Effects of Site-Directed Mutagenesis on Hemerythrin-like Protein Rv2633c" (2018). Honors Undergraduate Theses. 438.