Journal article
Authors list: Heyne, K; Herbst, J; Stehlik, D; Esteban, B; Lamparter, T; Hughes, J; Diller, R
Publication year: 2002
Pages: 1004-1016
Journal: Biophysical Journal
Volume number: 82
Issue number: 2
ISSN: 0006-3495
DOI Link: https://doi.org/10.1016/S0006-3495(02)75460-X
Publisher: Biophysical Society
Abstract:
Femtosecond time-resolved transient absorption spectroscopy was employed to characterize for the first time the primary photoisomerization dynamics of a bacterial phytochrome system in the two thermally stable states of the photocycle. The 85-kDa phytochrome Cph1 from the cyanobacterium Synechocystis PCC 6803 expressed in Escherichia coli was reconstituted with phycocyanobilin (Cph1-PCB) and phycoerythrobilin (Cph1-PEB). The red-light-absorbing form Pr of Cph1-PCB shows an similar to150 fs relaxation in the S-1 state after photoexcitation at 650 nm. The subsequent Z-E isomerization between rings C and D of the linear tetrapyrrole-chromophore is best described by a distribution of rate constants with the first moment at (16 ps)(-1). Excitation at 615 nm leads to a slightly broadened distribution. The reverse E-Z isomerization, starting from the far-red-absorbing form Pfr, is characterized by two shorter time constants of 0.54 and 3.2 ps. In the case of Cph1-PEB, double-bond isomerization does not take place, and the excited-state lifetime extends into the nanosecond regime. Besides a stimulated emission rise time between 40 and 150 fs, no fast relaxation processes are observed. This suggests that the chromophore-protein interaction along rings A, B, and C does not contribute much to the picosecond dynamics observed in Cph1-PCB but rather the region around ring D near the isomerizing C-15==C-16 double bond. The primary reaction dynamics of Cph1-PCB at ambient temperature is found to exhibit very similar features as those described for plant type A phytochrome, i.e., a relatively slow Pr, and a fast Pfr, photoreaction. This suggests that the initial reactions were established already before evolution of plant phytochromes began.
Citation Styles
Harvard Citation style: Heyne, K., Herbst, J., Stehlik, D., Esteban, B., Lamparter, T., Hughes, J., et al. (2002) Ultrafast dynamics of phytochrome from the cyanobacterium Synechocystis, reconstituted with phycocyanobilin and phycoerythrobilin, Biophysical Journal, 82(2), pp. 1004-1016. https://doi.org/10.1016/S0006-3495(02)75460-X
APA Citation style: Heyne, K., Herbst, J., Stehlik, D., Esteban, B., Lamparter, T., Hughes, J., & Diller, R. (2002). Ultrafast dynamics of phytochrome from the cyanobacterium Synechocystis, reconstituted with phycocyanobilin and phycoerythrobilin. Biophysical Journal. 82(2), 1004-1016. https://doi.org/10.1016/S0006-3495(02)75460-X