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

Abstract

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.

Detection of Incorporation of p-Coumaric Acid into Photoactive Yellow Protein Variants in Vivo

“…More recently, PYP has been adopted as a switching element in several fusion proteins designed as optogenetic tools. − Its small size and robustness make it relatively easy to link to effector domains resulting in soluble, well-behaved constructs. The relatively large conformational changes that PYP undergoes during signaling make it likely to affect the structure and function of fused target proteins.…”