Mutational analysis of the role of HPr in Listeria monocytogenes

Article Abstract:

Phosphotransferase system (PTS) complementation assays were performed to establish the effects of serine 46 phosphorylation on PTS activity in Listeria monocytogenes. Results indicated that conditions which favor phosphorylation of serine 46 decrease the PTS activity of L monocytogenes HPr and provide a mechanism for regulating the PTS. This was borne out by the substantial decrease in L monocytogenes HPr activity under conditions favoring serine 46 phosphorylation. HPr phosphorylated at serine 46 also does not seem to possess self-phosphatase activity.

Physiological aspects, Phosphorylation, Phosphatases

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Cloning and expression of the Listeria monocytogenes Scott A ptsH and ptsI genes, coding for HPr and enzyme I, respectively, of the phosphotransferase system

Article Abstract:

Genes encoding the HPr (ptsH) and enzyme I (ptsI) components of the Listeria monocytogenes phosphotransferase system (PTS) were isolated to examine the mechanisms of sugar transport in L. monocytogenes. The overexpressed and purified ptsH product was observed to complement PTS activity in Staphylococcus aureus extracts taken from ptsH mutants. Results indicate that the genes form an operon which is regulated by glucose and pH or by the by-products of glucose metabolism.

Genetic aspects, Gene expression, Bacterial proteins, Glucose, Glucose synthesis

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Collapse of the proton motive force in Listeria monocytogenes caused by a bacteriocin produced by Pediococcus acidilacti

Article Abstract:

The effects of the Pediococcus acidilacti JD1-23 bacteriocin, pediocin JD, on Listeria monocytogenes were investigated. The results showed that pediocin JD treatment could dissipate the pH gradients of the cell membrane, leading to a two-fold increase in the membrane's permeability to protons. The pH gradient dissipations could occur without cell lysis. These results suggest the pediocin JD acts to disrupt the proton motive force in L. monocytogenes.

Antibacterial agents, Electric properties, Cells, Cell membranes, Cell permeability, Electrophysiology

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