Studies on Thiol-Disulfide Oxidoreductases in Bacillus subtilis

Abstract: Bacillus subtilis is a model organism for endospore-forming gram-positive bacteria. Endospores are formed in response to nutrient starvation. They can resist harsh environments and last for long periods of time. Once nutrients again become available, the endospore can germinate and the vegetative life cycle be resumed. The outermost layers of the endospore are cortex and coat that protect the cell against various physical and chemical challenges. Thiol-disulfide oxidoreductases catalyse the formation and breakage of disulfide bonds in proteins. Disulfide bonds can function in stabilising the structure of a protein, but may also have a regulatory or catalytic role. Thiol-disulfide oxidoreductases have two cysteine residues in the active site. A disulfide bond between these residues is present as part of the catalytic cycle of the enzyme. This thesis concerns B. subtilis thiol-disulfide oxidoreductases involved in sporulation. It focuses on the functions of the two membrane proteins CcdA and StoA which both are involved in endospore cortex synthesis. An increased understanding of endospore maturation is of both theoretical and practical importance since bacterial spores have beneficial use but are also produced by some major pathogens.