Energy conservation via organohalide respiration in Sulfurospirillum multivorans

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In the anaerobe Sulfurospirillum multivorans the reductive dechlorination of the groundwater contaminant tetrachloroethene (PCE) is coupled to the formation of ATP via electron transport phosphorylation (organohalide respiration). The key enzyme is the reductive PCE dehalogenase (PceA), a periplasmic corrinoid-containing iron-sulfur protein. This project is aimed i) to elucidate the electron-transfer pathway to PceA and to identify and characterize the electron-conducting components (soluble or membrane-bound) between the hydrogenase or formate dehydrogenase and the reductive dehalogenase, ii) to reveal the role of PceB, the putative membrane anchor of PceA, and iii) to unravel the catalytic mechanism of the enzyme. To achieve these aims, differential proteomic studies and protein-protein interaction analyses will be used to identify the respiratory chain components. Studies with inverted vesicles will be performed to identify soluble electron donors for organohalide respiration. Defined mutagenesis of the Sulfurospirillum multivorans genome and subsequent spectroscopic investigations of the cell (or enzyme) variants will allow an in-depth exploration of the electron flow to the reductive dehalogenase (or within the enzyme). The data obtained in this project will provide crucial information about the fundamentals of microbial energy conservation coupled to reductive dechlorination.