Diverse supramolecular structures formed by self-assembling proteins of the B acillus subtilis spore coat.

Bacterial spores (endospores), such as those of the pathogens C lostridium difficile and B acillus anthracis, are uniquely stable cell forms, highly resistant to harsh environmental insults. B acillus subtilis is the best studied spore-former and we have used it to address the question of how the spore coat is assembled from multiple components to form a robust, protective superstructure. B . subtilis coat proteins ( CotY, CotE, CotV and CotW) expressed in E scherichia coli can arrange intracellularly into highly stable macro-structures through processes of self-assembly. Using electron microscopy, we demonstrate the capacity of these proteins to generate ordered one-dimensional fibres, two-dimensional sheets and three-dimensional stacks. In one case ( CotY), the high degree of order favours strong, cooperative intracellular disulfide cross-linking. Assemblies of this kind could form exquisitely adapted building blocks for higher-order assembly across all spore-formers. These physically robust arrayed units could also have novel applications in nano-biotechnology processes. [ABSTRACT FROM AUTHOR]