Global ETD Search

1	Axial Ligand Mutant: H229A Nguyen, Nhung Phuong 08 August 2008 (has links) Many pathogenic bacteria use their iron acquisition mechanisms to live inside hosts. Streptococcus pyogenes is a pathogenic bacterium that uses streptococcal iron acquisition ABC transporter to obtain heme. SiaA (HtsA, spy1795), a lipoprotein located on the cell surface, serves as a heme binding protein. To understand the iron-uptake mechanism, histidine 229, one of the two proposed axial ligands in SiaA, was mutated to alanine. SiaA H229A was expressed in E. coli, lysed by French Press, and purified by fast protein liquid chromatography (FPLC). SDS-PAGE indicated that pure protein was isolated. Nickel affinity FPLC gave purer H229A when 0.5 M imidazole was added to the binding buffer. Overall, histidine 229 is likely to be an axial ligand in wild type SiaA, as shown by the fact the mutant readily lost heme as evidenced by UV-vis spectra. SDS-PAGE FPLC Streptococcus pyogenes Heme nickel affinity homology modeling H229A bacterial iron acquisition PBP SiaA ABC transport E. coli axial ligand fast protein liquid chromatography alanine histidine