Structure and function of the C-terminal domain of MrpA in the Bacillus subtilis Mrp-antiporter complex--the evolutionary progenitor of the long horizontal helix in complex I.

MrpA and MrpD are homologous to NuoL, NuoM and NuoN in complex I over the first 14 transmembrane helices. In this work, the C-terminal domain of MrpA, outside this conserved area, was investigated. The transmembrane orientation was found to correspond to that of NuoJ in complex I. We have previously demonstrated that the subunit NuoK is homologous to MrpC. The function of the MrpA C-terminus was tested by expression in a previously used Bacillus subtilis model system. At neutral pH, the truncated MrpA still worked, but at pH 8.4, where Mrp-complex formation is needed for function, the C-terminal domain of MrpA was absolutely required

Photo-Electrochemical Communication Between Cyanobacteria and Osmium Redox Polymer Modified Electrodes

Most of the energy for all forms of life in the world originates from the sun, the ultimate energy source. Photosynthesis is the process by which green plants, algae and some bacteria convert sunlight into chemical energy with a quantum yield of about 100% [1]. Cyanobacteria, also called blue green algae, account for 20-30% of the primary photosynthetic activity on earth. The electrogenic conduit of cyanobacteria might be exploited to develop light sensitive devices that can convert solar energy into electricity [2]. Recently Rhodobacter capsulatus, the metabolically versatile purple bacteria, was shown to communicate with osmium redox polymer modified graphite electrodes [3]