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A thiol-reactive Ru(II) ion, not CO release, underlies the potent antimicrobial and cytotoxic properties of CO-releasing molecule-3

A thiol-reactive Ru(II) ion, not CO release, underlies the potent antimicrobial and cytotoxic properties of CO-releasing molecule-3
A thiol-reactive Ru(II) ion, not CO release, underlies the potent antimicrobial and cytotoxic properties of CO-releasing molecule-3
Carbon monoxide (CO)-releasing molecules (CORMs), mostly metal carbonyl compounds, are extensively used as experimental tools to deliver CO, a biological ‘gasotransmitter’ in mammalian systems. CORMs are also explored as potential novel antimicrobial drugs, effectively and rapidly killing bacteria in vitro and in animal models, but are reportedly benign towards mammalian cells. Ru-carbonyl CORMs, exemplified by CORM-3 (Ru(CO)3Cl(glycinate)), exhibit the most potent antimicrobial effects against Escherichia coli. We demonstrate that CORM-3 releases little CO in buffers and cell culture media and that the active antimicrobial agent is Ru(II), which binds tightly to thiols. Thus, thiols and amino acids in complex growth media – such as histidine, methionine and oxidised glutathione, but most pertinently cysteine and reduced glutathione (GSH) – protect both bacterial and mammalian cells against CORM-3 by binding and sequestering Ru(II). No other amino acids exert significant protective effects. NMR reveals that CORM-3 binds cysteine and GSH in a 1:1 stoichiometry with dissociation constants, Kd, of about 5 μM, while histidine, GSSG and methionine are bound less tightly, with Kdvalues ranging between 800 and 9000 μM. There is a direct positive correlation between protection and amino acid affinity for CORM-3. Intracellular targets of CORM-3 in both bacterial and mammalian cells are therefore expected to include GSH, free Cys, His and Met residues and any molecules that contain these surface-exposed amino acids. These results necessitate a major reappraisal of the biological effects of CORM-3 and related CORMs.
CO-releasing molecules, CORM-3, Gasotransmitters, Metallo-drugs, Novel antimicrobials
2213-2317
114-123
Southam, Hannah M.
68b5c136-748b-4d6c-9fa3-f10ed0b0aabe
Smith, Thomas W.
890d7d44-ab77-46cd-9c24-803936f6ac99
Lyon, Rhiannon L.
d42773ce-c119-4aed-a040-5b892d71a415
Liao, Chunyan
2253de59-34c7-4a62-bc27-54b59567a110
Trevitt, Clare R.
03561101-9a8a-413a-95f8-7c7497d4dd5e
Middlemiss, Laurence A.
770b3406-2556-46f8-a0de-bc215a9db7fd
Cox, Francesca L.
860d6dcb-88ac-4dd0-ab1d-53e6d2e853b4
Chapman, Jonathan A.
ff262f96-f68d-4fd2-8346-d898e46a9a92
El-Khamisy, Sherif F.
7ea3ea97-65fb-481d-8869-cf6ffb3c04bd
Hippler, Michael
14b18bbd-6ebd-48c1-b1f0-c8161a18e40f
Williamson, Michael P.
20df6883-3955-428b-bae2-98d40b440df4
Henderson, Peter J.F.
a7d59e7a-0f5a-4309-a530-e522e34dffea
Poole, Robert K.
5f1f3b79-cf45-4ae6-89cd-e4259c03ae56
Southam, Hannah M.
68b5c136-748b-4d6c-9fa3-f10ed0b0aabe
Smith, Thomas W.
890d7d44-ab77-46cd-9c24-803936f6ac99
Lyon, Rhiannon L.
d42773ce-c119-4aed-a040-5b892d71a415
Liao, Chunyan
2253de59-34c7-4a62-bc27-54b59567a110
Trevitt, Clare R.
03561101-9a8a-413a-95f8-7c7497d4dd5e
Middlemiss, Laurence A.
770b3406-2556-46f8-a0de-bc215a9db7fd
Cox, Francesca L.
860d6dcb-88ac-4dd0-ab1d-53e6d2e853b4
Chapman, Jonathan A.
ff262f96-f68d-4fd2-8346-d898e46a9a92
El-Khamisy, Sherif F.
7ea3ea97-65fb-481d-8869-cf6ffb3c04bd
Hippler, Michael
14b18bbd-6ebd-48c1-b1f0-c8161a18e40f
Williamson, Michael P.
20df6883-3955-428b-bae2-98d40b440df4
Henderson, Peter J.F.
a7d59e7a-0f5a-4309-a530-e522e34dffea
Poole, Robert K.
5f1f3b79-cf45-4ae6-89cd-e4259c03ae56

Southam, Hannah M., Smith, Thomas W., Lyon, Rhiannon L., Liao, Chunyan, Trevitt, Clare R., Middlemiss, Laurence A., Cox, Francesca L., Chapman, Jonathan A., El-Khamisy, Sherif F., Hippler, Michael, Williamson, Michael P., Henderson, Peter J.F. and Poole, Robert K. (2018) A thiol-reactive Ru(II) ion, not CO release, underlies the potent antimicrobial and cytotoxic properties of CO-releasing molecule-3. Redox Biology, 18, 114-123. (doi:10.1016/j.redox.2018.06.008).

Record type: Article

Abstract

Carbon monoxide (CO)-releasing molecules (CORMs), mostly metal carbonyl compounds, are extensively used as experimental tools to deliver CO, a biological ‘gasotransmitter’ in mammalian systems. CORMs are also explored as potential novel antimicrobial drugs, effectively and rapidly killing bacteria in vitro and in animal models, but are reportedly benign towards mammalian cells. Ru-carbonyl CORMs, exemplified by CORM-3 (Ru(CO)3Cl(glycinate)), exhibit the most potent antimicrobial effects against Escherichia coli. We demonstrate that CORM-3 releases little CO in buffers and cell culture media and that the active antimicrobial agent is Ru(II), which binds tightly to thiols. Thus, thiols and amino acids in complex growth media – such as histidine, methionine and oxidised glutathione, but most pertinently cysteine and reduced glutathione (GSH) – protect both bacterial and mammalian cells against CORM-3 by binding and sequestering Ru(II). No other amino acids exert significant protective effects. NMR reveals that CORM-3 binds cysteine and GSH in a 1:1 stoichiometry with dissociation constants, Kd, of about 5 μM, while histidine, GSSG and methionine are bound less tightly, with Kdvalues ranging between 800 and 9000 μM. There is a direct positive correlation between protection and amino acid affinity for CORM-3. Intracellular targets of CORM-3 in both bacterial and mammalian cells are therefore expected to include GSH, free Cys, His and Met residues and any molecules that contain these surface-exposed amino acids. These results necessitate a major reappraisal of the biological effects of CORM-3 and related CORMs.

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Accepted/In Press date: 23 June 2018
e-pub ahead of print date: 30 June 2018
Published date: September 2018
Keywords: CO-releasing molecules, CORM-3, Gasotransmitters, Metallo-drugs, Novel antimicrobials

Identifiers

Local EPrints ID: 425314
URI: http://eprints.soton.ac.uk/id/eprint/425314
ISSN: 2213-2317
PURE UUID: 18e6ae54-e176-4f1d-ab2e-c2591ff36037

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Date deposited: 12 Oct 2018 16:30
Last modified: 06 Oct 2020 19:07

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Contributors

Author: Hannah M. Southam
Author: Thomas W. Smith
Author: Rhiannon L. Lyon
Author: Chunyan Liao
Author: Clare R. Trevitt
Author: Laurence A. Middlemiss
Author: Francesca L. Cox
Author: Jonathan A. Chapman
Author: Sherif F. El-Khamisy
Author: Michael Hippler
Author: Michael P. Williamson
Author: Peter J.F. Henderson
Author: Robert K. Poole

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