TY - JOUR T1 - An homology- and coevolution-consistent structural model of bacterial copper-tolerance protein CopM supports function as a ‘metal sponge’ and suggests regions for metal-dependent interactions with other proteins JF - bioRxiv DO - 10.1101/013581 SP - 013581 AU - Luciano A. Abriata Y1 - 2015/01/01 UR - http://biorxiv.org/content/early/2015/01/18/013581.abstract N2 - Copper is essential for life but toxic, therefore all organisms control tightly its intracellular abundance. Bacteria have indeed whole operons devoted to copper resistance, with genes that code for efflux pumps, oxidases, etc. Recently, the CopM protein of the CopMRS operon was described as an important element for copper tolerance in Synechocystis. This protein consists of a domain of unknown function, and was suggested to act as a periplasmic/extracellular copper binder. This work describes a bioinformatic characterization of CopM including structural models based on homology modeling and on residue coevolution, to help expand on the recently reported experiments. The protein is predicted to be membrane-anchored, not secreted. Two disordered regions are predicted, both possibly involved in protein-protein interactions. The 3D models disclose a 4-helix bundle fold with several potential copper-binding sites, most of them largely buried inside the lumen of the bundle. Some of the predicted copper-binding sites involve residues from the disordered regions, suggesting that copper binding could induce structuring of these disordered regions and thus modulate the interactions they mediate. ER -