INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
¡TRABAJO EN EQUIPO! PRESENCIA DE COMPLEJOS DE CITOCROMOS EXTRACELULARES EN BIOFILMS ELECTRO-ACTIVOS DE Geobacter sulfurreducens
Autor/es:
ORDOÑEZ, MARÍA VICTORIA; INFOSSI, PASCALE; SCHROTT, GERMÁN DAVID; LOJOU, ELISABETH; BUSALMEN, JUAN PABLO
Reunión:
Congreso; X CONGRESO ARGENTINO DE MICROBIOLOGIA GENERAL SAMIGE; 2014
Institución organizadora:
Samige
Resumen:
The discovery of electro-active microorganisms in the past decade fastly became one of the top areas of study mainly due to the great number of technological applications these organisms present. Geobacter sulfurreducens is one of many anaerobic gram (?) bacteria capable of using extracellular insoluble electron acceptor like Fe (III) (hydro)oxides during respiration. Thesebacteria can also use a polarized electrode for this function, thus producing an electric current. The redox molecules involved in this process have been identified as type c cytochromes named Omc (Outter membrane cytochromes). Molecular aspects of this process as well as the mode of action of these redox molecules remain unclear. Aiming to gain more information we studied external soluble cytochromes Omc extracted from the extracellular matrix of electro-active  G. sulfurreducens biofilms developed over polarized electrodes. We first attempted to separate these proteins by hydroxyapatite chromatography and observed that,  unexpectedly, each elution contained more than one cytochrome. It has been previously described that respiratory proteins can and will, in many cases, associate forming multi-protein complexes necessary for the electron transport process to occur. Then, it may also be possible for G. sulfurreducens´s soluble external cytochromes to associate forming multi-protein redox complexes. Therefore we performed two dimensional blue native (2D-BN) gel electrophoresis stained with specific cytochrome staining to further corroborate the presence of Omc cytochrome complexes. Results indicated the presence of two high molecular weight extracellular redox complexes described here as COmc200 (MW≈200 kDa) and COmc150 (MW≈150 kDa). Also, a rather low molecular weight band, denominated COmc80 (MW≈80 kDa), was observed. Second dimension non-reducing  SDS-PAGE of each complex was performed to determine the components of each complex. Results showed that while COmc150 and COmc80 are composed by two cytochromes, COmc200 is composed of four different cytochromes. Interestely, all three complexes shared at least one component with the other two. This result may indicate a dynamic and possibly reversible protein interaction between these proteins. In this sense, we believe these redox complexes and their dynamic interaction are necessary for the redox process occurring outside the cell of electro-active bacteria