Insight into the environmental cues modulating the expression of bacterial toxin-antitoxin systems.

Bacteria require sophisticated sensing mechanisms to adjust their metabolism in response to stressful conditions and survive in hostile environments. Among them, toxin-antitoxin (TA) systems play a crucial role in bacterial adaptation to environmental challenges. TA systems are considered as stress-responsive elements, consisting of both toxin and antitoxin genes, typically organized in operons or encoded on complementary DNA strands.

Mechanism of action of -encoded type I toxins in : from membrane alterations to mesosome-like structures formation and bacterial lysis.

SprF1 is a type I toxin-antitoxin system located on prophage. It has previously been shown that the two toxins, SprG1 and SprG1, encoded by the gene, are two membrane-associated peptides structured in a single α-helix. Overexpression of these two peptides leads to growth inhibition and even death.

Impacts of the Type I Toxin-Antitoxin System, SprG1/SprF1, on Gene Expression.

Type I toxin-antitoxin (TA) systems are widespread genetic modules in bacterial genomes. They express toxic peptides whose overexpression leads to growth arrest or cell death, whereas antitoxins regulate the expression of toxins, acting as labile antisense RNAs. The () genome contains and expresses several functional type I TA systems, but their biological functions remain unclear.

A Novel Enterococcus faecalis Heme Transport Regulator (FhtR) Senses Host Heme To Control Its Intracellular Homeostasis.

is a commensal Gram-positive pathogen found in the intestines of mammals and is also a leading cause of severe infections occurring mainly among antibiotic-treated dysbiotic hospitalized patients. Like most intestinal bacteria, does not synthesize heme (in this report, heme refers to iron protoporphyrin IX regardless of the iron redox state). Nevertheless, environmental heme can improve fitness by activating respiration metabolism and a catalase that limits hydrogen peroxide stress.