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Influence of a Joining Helix on the BLUF Domain of the YcgF Photoreceptor from Escherichia coli
Author(s) -
Schroeder Claudia,
Werner Karla,
Otten Harm,
Krätzig Steffen,
Schwalbe Harald,
Essen LarsOliver
Publication year - 2008
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.200800280
Subject(s) - chemistry , escherichia coli , dark state , chromophore , moiety , helix (gastropod) , crystallography , domain (mathematical analysis) , stereochemistry , biophysics , biochemistry , biology , photochemistry , gene , physics , ecology , mathematical analysis , mathematics , atomic physics , snail
BLUF‐domain‐comprising photoreceptors sense blue light by utilizing FAD as a chromophore. The ycgF gene product of Escherichia coli is composed of a N‐terminal BLUF domain and a C‐terminal EAL domain, with the latter postulated to catalyze c‐di‐GMP hydrolysis. The linkage between these two domains involves a predominantly helical segment. Its role on the function of the YcgF photoreceptor domain was examined by characterizing BLUF domains with and without this segment and reconstituting them with either FAD, FMN or riboflavin. The stability of the light‐adapted state of the YcgF BLUF domain depends on the presence of this joining, helical segment and the adenosine diphosphate moiety of FAD. In contrast to other BLUF domains, two‐dimensional 1 H, 15 N and one‐dimensional 1 H NMR spectra of isotope‐labeled YcgF‐(1–137) revealed large conformational changes during reversion from the light‐ to the dark‐adapted state. Based on these results the function of the joining helix in YcgF during signal transfer and the role of the BLUF domain in regulating c‐di‐GMP levels is discussed.