Enterobactin protects E. coli from the ros-mediated toxic effects of pyochelin.

ADLER, CONRADO; PERALATA, DAIANA; MICHAVILA GABRIELA ; POMARES, MARÍA FERNANDA; CORBALÁN, NATALIA; DE CRISTÓBAL, RICARDO ; VINCENT, PAULA A.

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología molecular; 2011

Many bacteria produce the uptake systems for siderophores that they do not synthesize, allowing them to benefit from resources produced by other bacteria. Under iron-limited conditions, Escherichia coli K-12 produces the catecholate siderophore enterobactin in addition to the transport systems for a variety of other siderophores. However, it is not known whether there is an uptake system for pyochelin, a pseudomonad siderophore. In this report, we analyzed the moderate toxicity we observed for pyochelin on E. coli. An E. coli enterobactin mutant (DentE) showed elevated sensitivity to pyochelin and this was reversed by addition of enterobactin. Surprisingly, iron supplementation did not have a similar protective effect, ruling out iron starvation as an inhibitory mechanism. Addition of pyochelin to entE E. coli increased levels of reactive oxygen species (ROS), which were lowered in the presence of exogenous enterobactin and ascorbic acid. In addition, we observed that copper, but not iron or zinc, also reversed pyochelin toxicity. This reversal was not observed in a cueO background, thus implicating the multicopper oxidase CueO in protection from pyochelin. Together, these results suggest that siderophores may be used by bacteria to exert physiological and environmental roles other than iron acquisition.