AlmG, responsible for polymyxin resistance in pandemic Vibrio cholerae, is a glycyltransferase distantly related to lipid A late acyltransferases

摘要: Cationic antimicrobial peptides (CAMPs), such as polymyxins, are used a last-line defense in treatment of many bacterial infections. However, some bacteria have developed resistance mechanisms to survive these compounds. Current pandemic O1 Vibrio cholerae biotype El Tor is resistant whereas previous strain the Classical polymyxin-sensitive. The almEFG operon found V. confers >100-fold through aminoacylation lipopolysaccharide (LPS), expected decrease negatively charged surface outer membrane. This Gram-negative system bears striking resemblance related Gram-positive cell-wall remodeling strategy that also promotes CAMP resistance. Mutants defective AlmEF-dependent LPS modification exhibit reduced fitness vivo. Here, we present investigation AlmG, hitherto uncharacterized member AlmEFG pathway. Evidence for AlmG glycyl lipid substrate transferase activity demonstrated vivo by heterologous expression pathway enzymes specially engineered Escherichia coli strain. Development minimal keto-deoxyoctulosonate (Kdo)-lipid A domain E. was necessary facilitate chemical structure analysis and produce mimetic Kdo-lipid synthesized cholerae. Our biochemical studies support uniquely nuanced CAMPs provide more detailed description an enzyme pharmacologically relevant lysophosphospholipid acyltransferase (LPLAT) superfamily.