Expedited isolation of natural product peptidyl-tRNA hydrolase inhibitors from a Pth1 affinity column

New antibiotics and new antibiotic targets are needed to counter the development of bacterial drug resistance that threatens to return the human population to the pre-antibiotic era. Bacterial peptidyl-tRNA hydrolase (Pth1) is a promising new antibiotic target in the early stages of development. While inhibitory activity has been observed in a variety of natural products, bioactive fractionation has been a bottleneck for inhibitor isolation. To expedite the isolation of inhibitory compounds from complex mixtures, we constructed a Pth1 affinity column and used it to isolate inhibitory compounds from crude natural products. Recombinantly produced S. typhimurium Pth1 was covalently attached to a column matrix and the inhibitory activity isolated from ethanol extracts of Salvinia minima. The procedure reported here demonstrates that isolation of Pth1 inhibitory compounds from complex natural product extracts can be greatly expedited over traditional bioactive fractionation, decreasing time and expense. The approach is generally applicable to Pth1s from other bacterial species and opens an avenue to advance and accelerate inhibitor development against this promising antimicrobial target.