Journal article

Ultrafast dynamics of phytochrome from the cyanobacterium Synechocystis, reconstituted with phycocyanobilin and phycoerythrobilin


Authors listHeyne, K; Herbst, J; Stehlik, D; Esteban, B; Lamparter, T; Hughes, J; Diller, R

Publication year2002

Pages1004-1016

JournalBiophysical Journal

Volume number82

Issue number2

ISSN0006-3495

DOI Linkhttps://doi.org/10.1016/S0006-3495(02)75460-X

PublisherBiophysical 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 styleHeyne, 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 styleHeyne, 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


Last updated on 2025-21-05 at 15:12