Wednesday, February 7, 2024
The escalating crisis of antimicrobial resistance (AMR) necessitates the exploration of innovative therapeutic candidates. Our research program is pioneering an approach that targets the GroEL chaperonin system, a 60 kDa heat shock protein that plays a vital role maintaining protein homeostasis within bacteria. It operates in an ATP-dependent manner through the assistance of GroES, a co-chaperone that caps the active GroEL rings and encapsulates unfolded proteins within the GroEL-GroES chamber, allowing them to fold to their functional forms isolated from the cellular milieu. Inhibiting this molecular machine induces a cascade effect that disrupts numerous essential cellular functions and leads to bacterial death. This novel strategy holds great promise in combating bacteria resistant to existing antibiotics as GroEL has not been previously targeted by other drugs. Our initial high-throughput screening yielded ~400 diverse GroEL inhibitors. Subsequent development has produced several series of analogs that exhibit potent and selective inhibition of E. coli and members of the ESKAPE bacteria. These lead inhibitors have demonstrated exceptional ability to rapidly eliminate bacteria, including those within biofilms that are traditionally resistant to antibiotics, while exhibiting low toxicity to human cells. Recent efforts have focused on identifying inhibitor mechanisms of action and target engagement in cells. Using E. coli and S. aureus engineered to express GFP, whose folding is facilitated by GroEL, we have established target engagement of lead inhibitors in bacteria. Through CryoEM and LC-MS/MS techniques, we have identified binding sites for several inhibitor series, uncovering distinct mechanisms that interfere with GroEL's critical functional transitions. This knowledge has enabled us to validate on-target effects by expressing GroEL constructs resistant to inhibitors in E. coli. Our research is now advancing into animal studies to assess the safety and antibiotic efficacy of lead inhibitors. The potential impact of our GroEL-targeting antibiotic strategy extends beyond combating antimicrobial resistance in the ESKAPE pathogens. We are expanding this approach to address critical global health threats such as Mycobacterium tuberculosis and Trypanosoma brucei, the causative agent of African Sleeping Sickness. Thus, our GroEL-targeting antibiotic strategy offers a novel and promising avenue to combat a wide range of infectious organisms and tackle the growing challenge of antimicrobial resistance.
