Sistemas de homeostasis del cobre en las bacterias Gram negativas Escherichia coli y Vibrio cholerae

Copper is a transition metal essential for cellular metabolism, which is involved in many biological processes as a cofactor of several enzymes. Although essential, it is also toxic. For this reason, organisms in all kingdoms have developed homeostatic systems for its control. This element becomes more toxic under the anaerobic and slightly acidic conditions of the gastrointestinal tract forcing enterobacteria, and enteropathogens in particular, to develop mechanisms which allow them adapting to this element. In this work, after a short introduction about copper and its toxicity mechanisms, are described the copper homeostatic systems used for the Gram negative enteric bacterium Escherichia coli. The conservation of these systems in the enteropathogen Vibrio cholerae is analyzed by bioinformatic methods and recent findings related to copper tolerance in this microorganism are summarized. It was found that systems described in E. coli are partially conserved in V. cholerae, being present the CopA ATPase, responsible of copper homeostasis in the cytoplasm. However, it was not identified any homolog of multi-copper oxidase CueO nor the multicomponent system CusCFBA, both involved in copper homeostasis in the periplasmic space. This suggests the existence of other systems to control copper concentration in this compartment in V. cholerae.