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.
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http://dx.doi.org/10.1002/cbic.200800280 | DOI Listing |
ACS Phys Chem Au
November 2024
Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan.
OaPAC is a photoactivated enzyme that forms a homodimer. The two blue-light using flavin (BLUF) photoreceptor domains are connected to the catalytic domains with long coiled-coil C-terminal helices. Upon photoreception, reorganization of the hydrogen bonding network between Tyr6, Gln48, and the chromophore in the BLUF domain and keto-enol tautomerization of Gln48 are thought to occur.
View Article and Find Full Text PDFIUCrJ
November 2024
Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38044 Grenoble, France.
OaPAC is a recently discovered blue-light-using flavin adenosine dinucleotide (BLUF) photoactivated adenylate cyclase from the cyanobacterium Oscillatoria acuminata that uses adenosine triphosphate and translates the light signal into the production of cyclic adenosine monophosphate. Here, we report crystal structures of the enzyme in the absence of its natural substrate determined from room-temperature serial crystallography data collected at both an X-ray free-electron laser and a synchrotron, and we compare these structures with cryo-macromolecular crystallography structures obtained at a synchrotron by us and others. These results reveal slight differences in the structure of the enzyme due to data collection at different temperatures and X-ray sources.
View Article and Find Full Text PDFJ Phys Chem B
April 2024
Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Park 904, Amsterdam 1098 XH, The Netherlands.
Flavins play an important role in many oxidation and reduction processes in biological systems. For example, flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) are common cofactors found in enzymatic proteins that use the special redox properties of these flavin molecules for their catalytic or photoactive functions. The redox potential of the flavin is strongly affected by its (protein) environment; however, the underlying molecular interactions of this effect are still unknown.
View Article and Find Full Text PDFJ Phys Chem B
March 2024
Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
The blue light using the flavin (BLUF) domain is one of the smallest photoreceptors in nature, which consists of a unique bidirectional electron-coupled proton relay process in its photoactivation reaction cycle. This perspective summarizes our recent efforts in dissecting the photocycle into three elementary processes, including proton-coupled electron transfer (PCET), proton rocking, and proton relay. Using ultrafast spectroscopy, we have determined the temporal sequence, rates, kinetic isotope effects (KIEs), and concertedness of these elementary steps.
View Article and Find Full Text PDFNat Commun
January 2024
Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
Blue light using flavin (BLUF) photoreceptors respond to light via one of nature's smallest photo-switching domains. Upon photo-activation, the flavin cofactor in the BLUF domain exhibits multi-phasic dynamics, quenched by a proton-coupled electron transfer reaction involving the conserved Tyr and Gln. The dynamic behavior varies drastically across different species, the origin of which remains controversial.
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