![Author ORCID: We display the ORCID iD icon alongside authors names on our website to acknowledge that the ORCiD has been authenticated when entered by the user. To view the users ORCiD record click the icon. [opens in a new tab]](https://chemrxiv.org/engage/assets/public/chemrxiv/images/logos/orcid.png)
Abstract
The polymyxin colistin is an agent of last resort for treatment of severe infections by multiresistant Gram-negative opportunistic bacteria. Colistin resistance arises through covalent modification of lipid A disaccharide by phosphoethanolamine (PEtN) transferases, preventing colistin interaction. The Mobile Colistin Resistance (MCR) PEtN transferase is a plasmid-borne enzyme that is the major cause of colistin resistance in Escherichia coli, the most important antimicrobial resistant bacterial pathogen worldwide. Bacterial PEtN transferases like MCR comprise periplasmic catalytic and integral membrane domains, with mechanistic understanding largely based on studies of the former with limited information on the full-length enzyme. Previous investigations of a Neisseria meningitidis PEtN transferase identified that the catalytic domain can effectively dissociate from the transmembrane component and instead make extensive contacts with the membrane surface. Here we report extended molecular dynamics simulations of a model of full-length MCR-1, in a representative membrane comprising 80% of a PEtN donor substrate palmitoyloleoyl phosphoethanolamine (POPE) that explore the dynamic behavior of the enzyme and the impact upon it of zinc stoichiometry and of PEtN addition to the Thr285 acceptor residue. The results identify only limited movement of the two domains relative to one another, and that POPE can bind the likely “resting” state of the enzyme (mono-zinc with unmodified Thr285) in an orientation compatible with PEtN transfer to Thr285. Our data suggest domain motions in bacterial PEtN transferases to be condition-dependent and support a proposed “ping - pong” reaction mechanism with the mono-zinc enzyme competent to undertake the first stage.
Supplementary materials
Title
Supporting Information
Description
Equilibration parameters for molecular dynamics simulations of MCR-1 (Table S1); MCR-1 homology model used in simulations (Figure S1); Calpha RMSD values for unrestrained MD simulations (Figure S2); comparison of catalytic domain in simulations in isolation and in full-length MCR-1 (Figure S3); active site snapshots from simulations of mono-zinc MCR-1 (Figure S4); active site snapshots from unrestrained simulations of di-zinc MCR-1 with bound POPE (Figure S5); active site snapshots from restrained simulations of di-zinc MCR-1 (Figure S6).
Actions
