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A Single Residue within the MCR-1 Protein Confers Anticipatory Resilience

Frantz, Renate, Gwozdzinski, Konrad, Gisch, Nicolas, Doijad, Swapnil Prakash, Hudel, Martina, Wille, Maria, Abu Mraheil, Mobarak, Schwudke, Dominik, Imirzalioglu, Can, Falgenhauer, Linda, Ehrmann, Michael ORCID:, Chakraborty, Trinad and Weinert, Emily 2023. A Single Residue within the MCR-1 Protein Confers Anticipatory Resilience. Microbiology Spectrum 11 (3) , e03592-22. 10.1128/spectrum.03592-22

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The envelope stress response (ESR) of Gram-negative enteric bacteria senses fluctuations in nutrient availability and environmental changes to avert damage and promote survival. It has a protective role toward antimicrobials, but direct interactions between ESR components and antibiotic resistance genes have not been demonstrated. Here, we report interactions between a central regulator of ESR viz., the two-component signal transduction system CpxRA (conjugative pilus expression), and the recently described mobile colistin resistance protein (MCR-1). Purified MCR-1 is specifically cleaved within its highly conserved periplasmic bridge element, which links its N-terminal transmembrane domain with the C-terminal active-site periplasmic domain, by the CpxRA-regulated serine endoprotease DegP. Recombinant strains harboring cleavage site mutations in MCR-1 are either protease resistant or degradation susceptible, with widely differing consequences for colistin resistance. Transfer of the gene encoding a degradation-susceptible mutant to strains that lack either DegP or its regulator CpxRA restores expression and colistin resistance. MCR-1 production in Escherichia coli imposes growth restriction in strains lacking either DegP or CpxRA, effects that are reversed by transactive expression of DegP. Excipient allosteric activation of the DegP protease specifically inhibits growth of isolates carrying mcr-1 plasmids. As CpxRA directly senses acidification, growth of strains at moderately low pH dramatically increases both MCR-1-dependent phosphoethanolamine (PEA) modification of lipid A and colistin resistance levels. Strains expressing MCR-1 are also more resistant to antimicrobial peptides and bile acids. Thus, a single residue external to its active site induces ESR activity to confer resilience in MCR-1-expressing strains to commonly encountered environmental stimuli, such as changes in acidity and antimicrobial peptides. Targeted activation of the nonessential protease DegP can lead to the elimination of transferable colistin resistance in Gram-negative bacteria.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Biosciences
Publisher: American Society for Microbiology
ISSN: 2165-0497
Date of First Compliant Deposit: 16 May 2023
Date of Acceptance: 21 March 2023
Last Modified: 29 Jun 2023 16:24

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