Antibiotic Bactericidal Activity Is Countered by Maintaining pH Homeostasis in <named-content content-type="genus-species">Mycobacterium smegmatis</named-content>

ABSTRACT Antibiotics target specific biosynthetic processes essential for bacterial growth. It is intriguing that several commonalities connect the bactericidal activity of seemingly disparate antibiotics, such as the numerous conditions that confer broad-spectrum antibiotic tolerance. Whether antib...

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Autores principales: I. L. Bartek, M. J. Reichlen, R. W. Honaker, R. L. Leistikow, E. T. Clambey, M. S. Scobey, A. B. Hinds, S. E. Born, C. R. Covey, M. J. Schurr, A. J. Lenaerts, M. I. Voskuil
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Publicado: American Society for Microbiology 2016
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spelling oai:doaj.org-article:4bc7a2b252154e21a9d29ccf1851a0d12021-11-15T15:21:14ZAntibiotic Bactericidal Activity Is Countered by Maintaining pH Homeostasis in <named-content content-type="genus-species">Mycobacterium smegmatis</named-content>10.1128/mSphere.00176-162379-5042https://doaj.org/article/4bc7a2b252154e21a9d29ccf1851a0d12016-08-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mSphere.00176-16https://doaj.org/toc/2379-5042ABSTRACT Antibiotics target specific biosynthetic processes essential for bacterial growth. It is intriguing that several commonalities connect the bactericidal activity of seemingly disparate antibiotics, such as the numerous conditions that confer broad-spectrum antibiotic tolerance. Whether antibiotics kill in a manner unique to their specific targets or by a universal mechanism is a critical and contested subject. Herein, we demonstrate that the bactericidal activity of diverse antibiotics against Mycobacterium smegmatis and four evolutionarily divergent bacterial pathogens was blocked by conditions that worked to maintain intracellular pH homeostasis. Single-cell pH analysis demonstrated that antibiotics increased the cytosolic pH of M. smegmatis, while conditions that promoted proton entry into the cytosol prevented intracellular alkalization and antibiotic killing. These findings led to a hypothesis that posits antibiotic lethality occurs when antibiotics obstruct ATP-consuming biosynthetic processes while metabolically driven proton efflux is sustained despite the loss of proton influx via ATP synthase. Consequently, without a concomitant reduction in respiratory proton efflux, cell death occurs due to intracellular alkalization. Our findings indicate the effects of antibiotics on pH homeostasis should be considered a potential mechanism contributing to antibiotic lethality. IMPORTANCE Since the discovery of antibiotics, mortality due to bacterial infection has decreased dramatically. However, infections from difficult to treat bacteria such as Mycobacterium tuberculosis and multidrug-resistant pathogens have been on the rise. An understanding of the cascade of events that leads to cell death downstream of specific drug-target interactions is not well understood. We have discovered that killing by several classes of antibiotics was stopped by maintaining pH balance within the bacterial cell, consistent with a shared mechanism of antibiotic killing. Our findings suggest a mechanism of antibiotic killing that stems from the antibiotic’s ability to increase the pH within bacterial cells by disrupting proton entry without affecting proton pumping out of cells. Knowledge of the core mechanism necessary for antibiotic killing could have a significant impact on the development of new lethal antibiotics and for the treatment of recalcitrant and drug-resistant pathogens.I. L. BartekM. J. ReichlenR. W. HonakerR. L. LeistikowE. T. ClambeyM. S. ScobeyA. B. HindsS. E. BornC. R. CoveyM. J. SchurrA. J. LenaertsM. I. VoskuilAmerican Society for MicrobiologyarticleAntibioticsbactericidal activitymycobacteriapH homeostasisMicrobiologyQR1-502ENmSphere, Vol 1, Iss 4 (2016)
institution DOAJ
collection DOAJ
language EN
topic Antibiotics
bactericidal activity
mycobacteria
pH homeostasis
Microbiology
QR1-502
spellingShingle Antibiotics
bactericidal activity
mycobacteria
pH homeostasis
Microbiology
QR1-502
I. L. Bartek
M. J. Reichlen
R. W. Honaker
R. L. Leistikow
E. T. Clambey
M. S. Scobey
A. B. Hinds
S. E. Born
C. R. Covey
M. J. Schurr
A. J. Lenaerts
M. I. Voskuil
Antibiotic Bactericidal Activity Is Countered by Maintaining pH Homeostasis in <named-content content-type="genus-species">Mycobacterium smegmatis</named-content>
description ABSTRACT Antibiotics target specific biosynthetic processes essential for bacterial growth. It is intriguing that several commonalities connect the bactericidal activity of seemingly disparate antibiotics, such as the numerous conditions that confer broad-spectrum antibiotic tolerance. Whether antibiotics kill in a manner unique to their specific targets or by a universal mechanism is a critical and contested subject. Herein, we demonstrate that the bactericidal activity of diverse antibiotics against Mycobacterium smegmatis and four evolutionarily divergent bacterial pathogens was blocked by conditions that worked to maintain intracellular pH homeostasis. Single-cell pH analysis demonstrated that antibiotics increased the cytosolic pH of M. smegmatis, while conditions that promoted proton entry into the cytosol prevented intracellular alkalization and antibiotic killing. These findings led to a hypothesis that posits antibiotic lethality occurs when antibiotics obstruct ATP-consuming biosynthetic processes while metabolically driven proton efflux is sustained despite the loss of proton influx via ATP synthase. Consequently, without a concomitant reduction in respiratory proton efflux, cell death occurs due to intracellular alkalization. Our findings indicate the effects of antibiotics on pH homeostasis should be considered a potential mechanism contributing to antibiotic lethality. IMPORTANCE Since the discovery of antibiotics, mortality due to bacterial infection has decreased dramatically. However, infections from difficult to treat bacteria such as Mycobacterium tuberculosis and multidrug-resistant pathogens have been on the rise. An understanding of the cascade of events that leads to cell death downstream of specific drug-target interactions is not well understood. We have discovered that killing by several classes of antibiotics was stopped by maintaining pH balance within the bacterial cell, consistent with a shared mechanism of antibiotic killing. Our findings suggest a mechanism of antibiotic killing that stems from the antibiotic’s ability to increase the pH within bacterial cells by disrupting proton entry without affecting proton pumping out of cells. Knowledge of the core mechanism necessary for antibiotic killing could have a significant impact on the development of new lethal antibiotics and for the treatment of recalcitrant and drug-resistant pathogens.
format article
author I. L. Bartek
M. J. Reichlen
R. W. Honaker
R. L. Leistikow
E. T. Clambey
M. S. Scobey
A. B. Hinds
S. E. Born
C. R. Covey
M. J. Schurr
A. J. Lenaerts
M. I. Voskuil
author_facet I. L. Bartek
M. J. Reichlen
R. W. Honaker
R. L. Leistikow
E. T. Clambey
M. S. Scobey
A. B. Hinds
S. E. Born
C. R. Covey
M. J. Schurr
A. J. Lenaerts
M. I. Voskuil
author_sort I. L. Bartek
title Antibiotic Bactericidal Activity Is Countered by Maintaining pH Homeostasis in <named-content content-type="genus-species">Mycobacterium smegmatis</named-content>
title_short Antibiotic Bactericidal Activity Is Countered by Maintaining pH Homeostasis in <named-content content-type="genus-species">Mycobacterium smegmatis</named-content>
title_full Antibiotic Bactericidal Activity Is Countered by Maintaining pH Homeostasis in <named-content content-type="genus-species">Mycobacterium smegmatis</named-content>
title_fullStr Antibiotic Bactericidal Activity Is Countered by Maintaining pH Homeostasis in <named-content content-type="genus-species">Mycobacterium smegmatis</named-content>
title_full_unstemmed Antibiotic Bactericidal Activity Is Countered by Maintaining pH Homeostasis in <named-content content-type="genus-species">Mycobacterium smegmatis</named-content>
title_sort antibiotic bactericidal activity is countered by maintaining ph homeostasis in <named-content content-type="genus-species">mycobacterium smegmatis</named-content>
publisher American Society for Microbiology
publishDate 2016
url https://doaj.org/article/4bc7a2b252154e21a9d29ccf1851a0d1
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