Macromolecular crowding effects on reactions of TePixD (Tll0078).
To reveal macromolecular crowding effects on a chemical reaction of a BLUF (sensors of blue light using FAD) protein (PixD from a thermophilic cyanobacterium Thermosynechococcus elongatus BP-1 [TePixD, Tll0078]), the photoreaction was studied at various concentrations of the macromolecule Ficoll-70 by UV/Vis absorption spectroscopy and the pulsed laser-induced transient grating (TG) method. The absorption spectrum did not change with varying concentration of Ficoll-70. The crowding did not affect the quantum yield of the spectral red shift reaction, recovery rate of the product, rate constant of the volume change reaction and the magnitude of the volume change. However, the magnitude of the TG signal representing the diffusion-sensitive conformation change significantly increased on addition of Ficoll-70. This dependence was attributed to the crowding effect on the TePixD decamer-pentamer equilibrium in the solution. This result indicates that the TePixD reaction is more efficient in cellular than in in vitro conditions.
Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Japan.
Tsuguyoshi
T
Toyooka
Keisuke
K
Tanaka
Koji
K
Okajima
Masahiko
M
Ikeuchi
Satoru
S
Tokutomi
Masahide
M
Terazima
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000378:metabolism*; D004058:Diffusion / Q000187:drug effects / Q000528:radiation effects; D004926:Escherichia coli; D005362:Ficoll / Q000494:pharmacology; D005420:Flavoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008027:Light; D008968:Molecular Conformation / Q000187:drug effects / Q000528:radiation effects; D055668:Photochemical Processes / Q000528:radiation effects; D020283:Photoreceptors, Microbial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D058105:Polymerization / Q000528:radiation effects; D017434:Protein Structure, Tertiary / Q000187:drug effects / Q000528:radiation effects; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013054:Spectrophotometry, Atomic
D001426:Bacterial Proteins; D005420:Flavoproteins; D020283:Photoreceptors, Microbial; D011994:Recombinant Proteins; D005362:Ficoll