Project Summary/Abstract: Amyloidogenic Antibiotics New antibiotics are desperately needed against drug-resistant Gram-positive bacterial pathogens such as MRSA and VRE. Since its initial report in 2015, the peptide antibiotic teixobactin has generated considerable excitement because it kills Gram-positive bacteria without detectable resistance and is effective against bacteria that are resistant to other antibiotics. In studying teixobactin and its derivatives, the PI and coworkers have discovered that teixobactin achieves its remarkable activity through the formation of amyloid-like assemblies. These assemblies contain β-sheet dimer subunits that bind the pyrophosphate groups of lipid II and related cell wall precursors. The confluence of three components appears to endow teixobactin with its remarkable antibiotic activity: the amyloidogenic “tail,” the macrolactone ring, and the N-terminal methylammonium group. The amyloidogenic tail induces self-assembly, and the macrolactone ring and N-methylammonium group act in conjunction within the assemblies to bind the pyrophosphate groups. These three design principles will be used to create new peptide antibiotics in which the amyloidogenic tail of teixobactin is replaced with amyloid-forming sequences from other well-characterized amyloidogenic peptides. Modification of the lactone ring to a lactam and of the N-terminus to other cationic groups is envisioned to improve the pyrophosphate-binding capability of these novel antibiotics. The antibiotic activity, hemolytic activity, and cytotoxicity of the peptides produced will be analyzed in order to inform the development of drug candidates with good therapeutic windows. The peptides will be structurally characterized to further guide the antibiotic development. The proposed research will produce at least one new antibiotic derived from an amyloidogenic peptide with (1) good activity against MRSA and VRE and (2) low cytotoxicity and hemolytic activity, thus making it a candidate for further drug development. The results of this research will impact the field of antibiotics by developing and expanding upon a new antibiotic class — amyloidgenic antibiotics — that was identified in studying teixobactin. The success of this project will also pave the way for developing additional amyloidogenic antibiotics.