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Interaction Between N‐terminal Loop and β ‐Scaffold of Photoactive Yellow Protein †,‡
Author(s) -
Harigai Miki,
Kataoka Mikio,
Imamoto Yasushi
Publication year - 2008
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2008.00375.x
Subject(s) - chromophore , chemistry , kinetics , hydrophobic effect , biophysics , mutant , conformational change , protein–protein interaction , stereochemistry , photochemistry , biochemistry , physics , quantum mechanics , gene , biology
During the photoreaction cycle of photoactive yellow protein (PYP), a physiologically active intermediate (PYP M ) is formed as a consequence of global protein conformational change. Previous studies have demonstrated that the photocycle of PYP is regulated by the N‐terminal loop region, which is located across the central β ‐sheet from the p ‐coumaric acid chromophore. In this paper, the hydrophobic interaction between N‐terminal loop and β ‐sheet was studied by characterizing PYP mutants of the hydrophobic residues. The rate constants and structural changes of the photocycle of L15A and L23A possibly participating in such an interaction were more similar to wild‐type than F6A, showing that the CH/ π interaction between Phe6 and Lys123 is the most essential as reported previously. To better understand the interactions between N‐terminal tail and β ‐sheet of PYP, Phe6 and Phe121 were replaced by Cys and linked by a disulfide bond. Since the photocycle kinetics, structural change and thermal stability of F6C/F121C were similar to F6A, the CH/ π interaction between Phe6 and Lys123 is not substitutable. It is likely that the detachment of position 6 from position 123 substantially alters the nature of PYP.