Jump to Main Content
Bioenergetic Mechanism for Nisin Resistance, Induced by the Acid Tolerance Response of Listeria monocytogenes
- Bonnet, Marcelo, Rafi, Mohamed M., Chikindas, Michael L., Montville, Thomas J.
- Applied and environmental microbiology 2006 v.72 no.4 pp. 2556-2563
- Listeria monocytogenes, food pathogens, acid tolerance, nisin, biological resistance, energy metabolism, cell membranes, membrane potential, pH, hydrogen ions, ion transport, adenosine triphosphate, hydrolysis, H-transporting ATPase
- This study examined the bioenergetics of Listeria monocytogenes, induced to an acid tolerance response (ATR). Changes in bioenergetic parameters were consistent with the increased resistance of ATR-induced (ATR⁺) cells to the antimicrobial peptide nisin. These changes may also explain the increased resistance of L. monocytogenes to other lethal factors. ATR⁺ cells had lower transmembrane pH ([Delta]pH) and electric potential ([Delta][psi]) than the control (ATR⁻) cells. The decreased proton motive force (PMF) of ATR⁺ cells increased their resistance to nisin, the action of which is enhanced by energized membranes. Paradoxically, the intracellular ATP levels of the PMF-depleted ATR⁺ cells were [approximately]7-fold higher than those in ATR⁻ cells. This suggested a role for the F[subscript o]F₁ ATPase enzyme complex, which converts the energy of ATP hydrolysis to PMF. Inhibition of the F[subscript o]F₁ ATPase enzyme complex by N'-N'-1,3-dicyclohexylcarbodiimide increased ATP levels in ATR⁻ but not in ATR⁺ cells, where ATPase activity was already low. Spectrometric analyses (surface-enhanced laser desorption ionization-time of flight mass spectrometry) suggested that in ATR⁺ listeriae, the downregulation of the proton-translocating c subunit of the F[subscript o]F₁ ATPase was responsible for the decreased ATPase activity, thereby sparing vital ATP. These data suggest that regulation of F[subscript o]F₁ ATPase plays an important role in the acid tolerance response of L. monocytogenes and in its induced resistance to nisin.