Insights into the Mechanistic Basis of Plasmid-Mediated Colistin Resistance from Crystal Structures of the Catalytic Domain of MCR-1
Citations Over TimeTop 10% of 2017 papers
Abstract
The polymixin colistin is a "last line" antibiotic against extensively-resistant Gram-negative bacteria. Recently, the mcr-1 gene was identified as a plasmid-mediated resistance mechanism in human and animal Enterobacteriaceae, with a wide geographical distribution and many producer strains resistant to multiple other antibiotics. mcr-1 encodes a membrane-bound enzyme catalysing phosphoethanolamine transfer onto bacterial lipid A. Here we present crystal structures revealing the MCR-1 periplasmic, catalytic domain to be a zinc metalloprotein with an alkaline phosphatase/sulphatase fold containing three disulphide bonds. One structure captures a phosphorylated form representing the first intermediate in the transfer reaction. Mutation of residues implicated in zinc or phosphoethanolamine binding, or catalytic activity, restores colistin susceptibility of recombinant E. coli. Zinc deprivation reduces colistin MICs in MCR-1-producing laboratory, environmental, animal and human E. coli. Conversely, over-expression of the disulphide isomerase DsbA increases the colistin MIC of laboratory E. coli. Preliminary density functional theory calculations on cluster models suggest a single zinc ion may be sufficient to support phosphoethanolamine transfer. These data demonstrate the importance of zinc and disulphide bonds to MCR-1 activity, suggest that assays under zinc-limiting conditions represent a route to phenotypic identification of MCR-1 producing E. coli, and identify key features of the likely catalytic mechanism.
Related Papers
- → Molecular Epidemiology and Colistin Resistant Mechanism of mcr-Positive and mcr-Negative Clinical Isolated Escherichia coli(2017)106 cited
- → Molecular epidemiology of isolates with multiple mcr plasmids from a pig farm in Great Britain: the effects of colistin withdrawal in the short and long term(2018)66 cited
- → Detection of mcr -Mediated Colistin Resistance in Escherichia coli Isolates from Pigs in Small-Scale Farms in Cambodia(2019)13 cited
- → Progress in plasmid-mediated colistin resistance gene mcr-1(2018)
- → Surveillance of colistin-resistance and mcr genes in multi-drug resistant Enterobacteriaceae(2021)