Clift Research Project Summary

The discovery of new antibiotic agents that operate through novel modes of action is regarded as potential solution to combat growing bacterial resistance. Recently, inhibition of FtsZ polymerization has emerged as a promising new target for the development of antibiotics. FtsZ is a highly conserved, prokaryotic, tubulin-like protein that undergoes self-polymerization to enable bacterial cell division. Berberine and tetrahydroprotoberberine (THPB) possess modest affinity for FtsZ that imbues these alkaloid natural products with antibacterial properties. Semi-synthesis has enabled the preparation of relatively potent (MIC = 1 μg/mL) berberine derivatives; however, semi-synthesis is inherently limited by the natural reactivity of berberine itself and the lack of a flexible and concise synthetic approach to access berberine analogs has left significant gaps in what is known about the structure−activity relationships that exist between berberine and FtsZ. The overall objective of this proposal is to design, synthesize and test previously inaccessible berberine-like compounds to discover new antibiotics that target bacterial cell division. Three aims are proposed to pursue this objective:

Specific Aim #1: Prioritize synthetic targets by using synthesis in silico to generate a custom compound library that will be used for virtual screening against FtsZ polymerization.

Specific Aim #2: Develop a concise and flexible total synthesis of berberine and THPB, and use this synthetic route to access a wide range of previously inaccessible analogs.

Specific Aim #3: Evaluate fully synthetic berberine analogs in bacterial growth inhibition assays, FtsZ GTPase activity assays, and FtsZ polymerization assays to identify antibiotic compounds that operate through inhibition of cell division.

The major innovations include 1) the development of a concise and flexible synthetic route that will facilitate the rapid preparation of previously inaccessible berberine and THPB analogs, and 2) the use of an in silico synthesis/virtual screening approach to prioritize target compounds. The proposed work is significant because the development of novel small molecule inhibitors of cell division has the potential to deliver 1) chemical probes that will enable future studies on the therapeutic potential of FtsZ inhibitors, and 2) hit compounds that define a new class of antibiotic therapeutics.