Fe-S Cluster Biosynthesis Controls Uptake of Aminoglycosides in a ROS-Less Death Pathway

Abstract

All bactericidal antibiotics were recently proposed to kill by inducing reactive oxygen species (ROS) production, causing destabilization of iron-sulfur (Fe-S) clusters and generating Fenton chemistry. We find that the ROS response is dispensable upon treatment with bactericidal antibiotics. Furthermore, we demonstrate that Fe-S clusters are required for killing only by aminoglycosides. In contrast to cells, using the major Fe-S cluster biosynthesis machinery, ISC, cells using the alternative machinery, SUF, cannot efficiently mature respiratory complexes I and II, resulting in impendence of the proton motive force (PMF), which is required for bactericidal aminoglycoside uptake. Similarly, during iron limitation, cells become intrinsically resistant to aminoglycosides by switching from ISC to SUF and down-regulating both respiratory complexes. We conclude that Fe-S proteins promote aminoglycoside killing by enabling their uptake.

Antibiotics induce redox-related physiological alterations as part of their lethality

“…Interesting recent work has illustrated that phenotypes such as cell death, mutagenesis, oxidative stress, and related activation of OxyR can all be reduced, depending on the method of culturing (101). These findings are consistent with a recent commentary on the current ROS debate (93), which suggested that differences in experimental conditions may help explain the incongruent conclusions regarding the ROS hypothesis reached by others based on the absence or minimal extent of such phenotypes (49)(50)(51). Our related recent work involving metabolic modeling of ROS production predicted and experimentally confirmed that even small increases in ROS levels can enhance antibiotic lethality (92).…”

“…These results, along with recent observations that kanamycin can damage DNA bases (26) and induce SOS response in strains with mutated 8-oxo-dG-processing genes (mutM, mutY, and mutT) (96), highlight a DNA-damaging component to aminoglycoside lethality, as is consistent with previous MutT results (25). More broadly, these findings suggest that suppressive alterations to proton motor force cannot wholly explain anaerobic protection against aminoglycoside lethality (49)(50)(51).…”

“…Specifically, these recent studies (49)(50)(51) are predicated on the notion that ROS are the sole arbiters of antibiotic lethality, thereby implying that the model suggests that antibiotics do not kill by disrupting their well-established, target-specific processes. However, the evolving model is completely consistent with the literature indicating that bactericidal antibiotics are capable of inducing lethal cellular damage via interference with target-specific processes, ultimately…”

Single-cell, real-time detection of oxidative stress induced in Escherichia coli by the antimicrobial peptide CM15

“…Oxidative damage was evidently essential for complete killing of cells. The initial results have been challenged (8)(9)(10), and very recently these challenges have been refuted (11). Evidently, oxidative stress contributes to the lethality of a variety of antimicrobial agents (12,13), including at least some antimicrobial peptides.…”

Du fer et du soufre dans les protéines

“…coli, fabriquant ses centres Fe-S grâce à la machinerie SUF, présentait un degré de résistance aux aminoglycosides plus élevé que la même souche les fabriquant avec la machinerie ISC [47]. Les bases moléculaires de cette observation surprenante se trouvent dans les mécanismes associant transport et force proton motrice (PMF).…”