A retroprotein has exactly the same sequence as a naturally-occurring protein, except that the direction in which the polypeptide backbone runs through the protein is exactly the opposite of what it was in the first place. In this paper, we describe the reversal of another beta sheet-based protein, the GroES co-chaperone from Escherichia coli. Like GroES, retroGroES folds and assembles into beta sheet-based structure, and small multimeric assemblies, but with considerable content of polyproline type-II structure. Unlike any regular globular protein, however, retroGroES displays greater structural content upon heating, with PP-II structure converting into beta sheet-based structure.

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