Enterobactin as an intracellular oxidative stress protector allows Escherichia coli colony formation

PERALATA, DAIANA; ADLER, CONRADO; CORBALÁN, NATALIA; POMARES, MARÍA FERNANDA; VINCENT, PAULA .A

Buenos Aires

Congreso; XLIX Reunión Anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología molecular; 2013

To acquire iron, Escherichia coli synthesize the catechol siderophore enterobactin, along with its specific transport system. Previously, we showed that an E. coli entE mutant is unable to develop colonies on agarized M9 medium (M9A). This phenotype was related to an increment in the oxidative stress and was reverted by enterobactin suplementation and by anaerobic culture conditions. In this work, we demonstrate that enterobactin needs to be hydrolyzed, after reaching the cell cytoplasm, in order to allow colony development. We observed that a fes mutant, unable to release iron from the enterobactin-iron complex, did not develop colonies in M9A and showed increased ROS levels compared with the wild type strain. The absence of colonies was reverted by addition of the reducing agent ascorbic acid. Meanwhile, enterobactin supplementation did not recover fes strain colony formation. On the other hand, we observed that a group of aromatic amino acids when added to the medium, allowed normal colony growth of the entE mutant. Furthermore, tryptophan and tyrosine reduced the increment of ROS levels in entE cells growing in M9. These results agree with our hypothesis implying enterobactin in the oxidative stress protection and in a critical role on E. coli colony development in M9A.