The antibacterial action of protamine: evidence for disruption of cytoplasmic membrane energization in Salmonella typhimurium

Article Abstract:

Protamine, a polycationic peptide found in the nuclei of sperm of different animal species, disrupts energy transduction and nutrient uptake functions, with cytoplasmic membrane as its target. An examination of its mechanism of action showed that it exerts its antibacterial effect without causing cell lysis or permeabilization of the cytoplasmic membrane. The peptide caused suppression of proline uptake, rapid efflux of proline from preloaded cells and a reduction in the cellular ATP content. Cells treated with protamine also lost the ability to accumulate leucine, then were unable to undertake protein synthesis.

Analysis, Peptides, Cell membranes

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Mg2+ as an extracellular signal: environmental regulation of Salmonella virulence

Article Abstract:

Magnesium ions were found to limit the ability of Salmonella typhimurium to defend itself against antimicrobial peptides such as defensin and magainin 2. The presence of magnesium ions disables a two-component protein that controls the expression of other proteins involved in cell defense. One component, the PhoQ protein, has a structure that extends outside the cytoplasm and which has been identified as the part that is altered upon contact with magnesium ions.

Ions, Magnesium, Magnesium (Metal)

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Pathogenicity islands: bacterial evolution in quantum leaps

Article Abstract:

Pathogenicity islands are segments of chromosome that are rarely detected in non-pathogenic organisms. They come in various lengths but they commonly accommodate large clusters of genes contributing a particular virulence phenotype. A normally benign organism can change into a pathogen just by the incorporation of a pathogenicity island. The deletion of pathogenicity islands is being eyed as a regulatory mechanism to control expression of virulence genes.

Research, Virulence (Microbiology), Pathogenic microorganisms

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