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Synthesis of a polymyxin derivative for photolabeling studies in the gram-negative bacterium Escherichia coli


Robinson, J A; van der Meijden, B (2015). Synthesis of a polymyxin derivative for photolabeling studies in the gram-negative bacterium Escherichia coli. Journal of Peptide Science, 21(3):231-235.

Abstract

The antimicrobial activity of polymyxins against Gram-negative bacteria has been known for several decades, but the mechanism of action leading to cell death has not been fully explored. A key step after binding of the antibiotic to lipopolysaccharide (LPS) exposed at the cell surface is 'self-promoted uptake' across the outer membrane (OM), in which the antibiotic traverses the asymmetric LPS-phospholipid bilayer before reaching the periplasm and finally targeting and disrupting the bacterial phospholipid inner membrane. The work described here was prompted by the hypothesis that polymyxins might interact with proteins in the OM, as part of their self-promoted uptake and permeabilizing effects. One way to test this is through photolabeling experiments. We describe the design and synthesis of a photoprobe based upon polymyxin B, containing photoleucine and an N-acyl group with a terminal alkyne suitable for coupling to a biotin tag using click chemistry. The resulting photoprobe retains potent antimicrobial activity, and in initial photolabeling experiments with Escherichia coli ATCC25922 is shown to photolabel several OM proteins. This photoprobe might be a valuable tool in more detailed studies on the mechanism of action of this family of antibiotics.

Abstract

The antimicrobial activity of polymyxins against Gram-negative bacteria has been known for several decades, but the mechanism of action leading to cell death has not been fully explored. A key step after binding of the antibiotic to lipopolysaccharide (LPS) exposed at the cell surface is 'self-promoted uptake' across the outer membrane (OM), in which the antibiotic traverses the asymmetric LPS-phospholipid bilayer before reaching the periplasm and finally targeting and disrupting the bacterial phospholipid inner membrane. The work described here was prompted by the hypothesis that polymyxins might interact with proteins in the OM, as part of their self-promoted uptake and permeabilizing effects. One way to test this is through photolabeling experiments. We describe the design and synthesis of a photoprobe based upon polymyxin B, containing photoleucine and an N-acyl group with a terminal alkyne suitable for coupling to a biotin tag using click chemistry. The resulting photoprobe retains potent antimicrobial activity, and in initial photolabeling experiments with Escherichia coli ATCC25922 is shown to photolabel several OM proteins. This photoprobe might be a valuable tool in more detailed studies on the mechanism of action of this family of antibiotics.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:March 2015
Deposited On:07 Jan 2016 07:43
Last Modified:05 Apr 2016 19:49
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:1075-2617
Funders:SNF
Additional Information:This is the accepted version of the following article: Synthesis of a polymyxin derivative for photolabeling studies in the gram-negative bacterium Escherichia coli, which has been published in final form at http://dx.doi.org/10.1002/psc.2736.
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1002/psc.2736
PubMed ID:25640745

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