Deep Mutational Scanning Reveals the Active-Site Sequence Requirements for the Colistin Antibiotic Resistance Enzyme MCR-1

Abstract

gene encodes a transmembrane phosphoethanolamine (PEA) transferase that modifies lipid A to block the binding of polymyxin antibiotics. We utilized random mutagenesis coupled with next-generation sequencing to determine the amino acid sequence requirements of 23 residues in and near the active site of MCR-1. We show that the enzyme has stringent sequence requirements, with 75% of the residues examined being essential for function. Coupled with the finding that these residues are largely conserved among PEA enzymes, the results suggest inhibitors that bind near these sites will broadly inhibit MCR-1 and other enzymes of this class.

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