Issue 17, 2021

Catalytic mechanism of the colistin resistance protein MCR-1

Abstract

The mcr-1 gene encodes a membrane-bound Zn2+-metalloenzyme, MCR-1, which catalyses phosphoethanolamine transfer onto bacterial lipid A, making bacteria resistant to colistin, a last-resort antibiotic. Mechanistic understanding of this process remains incomplete. Here, we investigate possible catalytic pathways using DFT and ab initio calculations on cluster models and identify a complete two-step reaction mechanism. The first step, formation of a covalent phosphointermediate via transfer of phosphoethanolamine from a membrane phospholipid donor to the acceptor Thr285, is rate-limiting and proceeds with a single Zn2+ ion. The second step, transfer of the phosphoethanolamine group to lipid A, requires an additional Zn2+. The calculations suggest the involvement of the Zn2+ orbitals directly in the reaction is limited, with the second Zn2+ acting to bind incoming lipid A and direct phosphoethanolamine addition. The new level of mechanistic detail obtained here, which distinguishes these enzymes from other phosphotransferases, will aid in the development of inhibitors specific to MCR-1 and related bacterial phosphoethanolamine transferases.

Graphical abstract: Catalytic mechanism of the colistin resistance protein MCR-1

Supplementary files

Article information

Article type
Communication
Submitted
23 Dec 2020
Accepted
11 Feb 2021
First published
16 Feb 2021
This article is Open Access
Creative Commons BY license

Org. Biomol. Chem., 2021,19, 3813-3819

Catalytic mechanism of the colistin resistance protein MCR-1

R. Suardíaz, E. Lythell, P. Hinchliffe, M. van der Kamp, J. Spencer, N. Fey and A. J. Mulholland, Org. Biomol. Chem., 2021, 19, 3813 DOI: 10.1039/D0OB02566F

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