ENTEROBACTIN SIDEROPHORE IS INVOLVED IN E. coli COPPER DETOXIFICATION

PERALTA DAIANA ROMINA; DE GREGORIO PRISCILLA ROMINA; POMARES MARÍA FERNANDA; ADLER CONRRADO; CORBALÁN NATALIA SOLEDAD; VINCENT PAULA ANDREA

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

Copper is a metal that catalyzes the formation of highly reactive oxygen species (ROS) in cell through Fenton-like reaction, leading to an oxidative damage in lipids, DNA and proteins. Previous reports indicate that catecholate-containing molecules such as E. coli enterobactin siderophore, can react with Cu2+ and reduce it to Cu+. Copper reduction by enterobactin would result toxic because lead to facilitate Cu+ uptake and increased ROS production into cells. We previously reported that enterobactin confers protection against varioussources of oxidative stress such us Pseudomonad siderophore pyochelin, H2O2 and paraquat, independently of its ability to facilitate iron uptake. In this work, we analyzed the role of enterobactin in copper toxicity. To test this, we evaluated the sensitivity of different E. coli strains mutant in enterobactin metabolism to copper. We observed that strains impaired in enterobactin production, uptake and hydrolysis were more susceptible to copper damage compared to wild-type strain. Incubation in anaerobic condition or addition ofcatalase enzyme to the media protected cells lacking enterobactin from copper toxicity. We also found that spent medium from strain mutants showing increased catechol production, exhibited high copper reduction activity. Nevertheless, these strains had the same copper sensitivity than those mutants that do not produce catechols and, in consequence, have no copper reduction activity. Besides, we observed that entE, fepG and fes mutants showed increased ROSlevels when they grew in presence of copper compared to wild-type strain. Enterobactin supplementation reduced copper sensitivity and ROS levels in the entE mutant but did not have any protective effect on the fepG and fes mutants. Results suggest that enterobactin plays a role in copper cell detoxification and indicate that enterobactin must to be internalized and hydrolyzed to confer a full protection, possibly by reducing the metal-induced oxidative stress.