Structure of the catalytic domain of the colistin resistance enzyme MCR-1.
Stojanoski VVerna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.
Sankaran BBerkeley Center for Structural Biology, Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA.
Prasad BVVerna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.
Poirel LDepartment of Medicine, Medical and Molecular Microbiology "Emerging Antibiotic Resistance" Unit and European INSERM Laboratory, IAME, University of Fribourg, Fribourg, Switzerland.
Nordmann PDepartment of Medicine, Medical and Molecular Microbiology "Emerging Antibiotic Resistance" Unit and European INSERM Laboratory, IAME, University of Fribourg, Fribourg, Switzerland.
Palzkill TVerna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA. timothyp@bcm.edu.
English
BACKGROUND Due to the paucity of novel antibiotics, colistin has become a last resort antibiotic for treating multidrug resistant bacteria. Colistin acts by binding the lipid A component of lipopolysaccharides and subsequently disrupting the bacterial membrane. The recently identified plasmid-encoded MCR-1 enzyme is the first transmissible colistin resistance determinant and is a cause for concern for the spread of this resistance trait. MCR-1 is a phosphoethanolamine transferase that catalyzes the addition of phosphoethanolamine to lipid A to decrease colistin affinity.
RESULTS The structure of the catalytic domain of MCR-1 at 1.32 Å reveals the active site is similar to that of related phosphoethanolamine transferases.
CONCLUSIONS The putative nucleophile for catalysis, threonine 285, is phosphorylated in cMCR-1 and a zinc is present at a conserved site in addition to three zincs more peripherally located in the active site. As noted for catalytic domains of other phosphoethanolamine transferases, binding sites for the lipid A and phosphatidylethanolamine substrates are not apparent in the cMCR-1 structure, suggesting that they are present in the membrane domain.