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Duplication of a Single Strand in a β‑Sheet Can Produce a New Switching Function in a Photosensory Protein

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journal contribution
posted on 13.06.2018, 00:00 by Anil Kumar, Sergiy Nokhrin, Ryan M. Woloschuk, G. Andrew Woolley
Duplication of a single β-strand that forms part of a β-sheet in photoactive yellow protein (PYP) was found to produce two approximately isoenergetic protein conformations, in which either the first or the second copy of the duplicated β-strand participates in the β-sheet. Whereas one conformation (big-loop) is more stable at equilibrium in the dark, the other conformation (long-tail) is populated after recovery from blue light irradiation. By appending a recognition motif (E-helix) to the C-terminus of the protein, we show that β-strand duplication, and the resulting possibility of β-strand slippage, can lead to a new switchable protein–protein interaction. We suggest that β-strand duplication may be a general means of introducing two-state switching activity into protein structures.