Ford, Jordan

Jordan is in the Biochemistry, Molecular and Structural Biology Graduate Program, and joined the CMB Training Program in 2022.
Mentor: Dr. Robert Clubb
The increase in antimicrobial resistance in pathogenic bacteria has created a looming public health crisis. Novel “antivirulence” compounds that target conserved microbial virulence pathways are particularly promising therapeutics, as they would disarm microorganisms that cause infectious disease but exert limited selective pressure that leads to antibiotic resistance. One such targetable virulence pathway is iron scavenging, as bacterial pathogens must acquire iron from their host in order to proliferate. My work focuses on heme scavenging by Corynebacterium diphtheriae, the etiological agent of diphtheria disease in humans. C. diphtheriae acquires heme from human hemoglobin using surface proteins that bind heme through Conserved Region (CR) domains.
This CR-CR transfer complex presumably forms via fleeting, protein-protein interactions. I propose to use paramagnetic relaxation enhancement (PRE) NMR to define the relative orientation and long-distance intermolecular restraints of the CR-CR transfer complex. The site-specific conjugation of paramagnetic spin labels can enhance relaxation rates of nearby nuclei, which leads to line-broadening effects in a distance-dependent manner, potentially giving long-distance information on nuclei up to 25 Å away. Back-calculated PRE distance restraints will be used to inform molecular docking of the holo-CR donor against the apo-CR acceptor before more rigorous molecular dynamics simulations are used to model the mechanism of the heme transfer reaction.
I also aim to extend the in vitro and in silico results above into a cellular system. I seek to probe the heme-uptake pathway in C. diphtheriae culture through the targeted knockout of individual surface components, as well as on a mechanistic level through mutations that disrupt CR self-association but not heme binding affinity. If indeed heme is rapidly relayed via a transient CR-CR complex in vivo, disruption of the encounter-complex interface defined by the PRE experiments should lead to reduced efficiency of iron import when grown on hemoglobin, even if heme binding affinity is left intact. Overall, this work has the potential to identify vulnerabilities in an important nutrient uptake system that could lay the groundwork for the development of novel antivirulence therapeutics that target conserved iron acquisition pathways.