A1 Journal article (refereed)
Excitation-Wavelength Dependent Photocycle Initiation Dynamics Resolve Heterogeneity in the Photoactive Yellow Protein from Halorhodospira halophila (2018)

Mix, L. T., Carroll, E. C., Morozov, D., Pan, J., Gordon, W. R., Philip, A., . . . Larsen, D. S. (2018). Excitation-Wavelength Dependent Photocycle Initiation Dynamics Resolve Heterogeneity in the Photoactive Yellow Protein from Halorhodospira halophila. Biochemistry, 57 (1), 1733-1747. doi:10.1021/acs.biochem.7b01114

JYU authors or editors

Publication details

All authors or editors: Mix, L. Tyler; Carroll, Elizabeth C.; Morozov, Dmitry; Pan, Jie; Gordon, Wendy Ryan; Philip, Andrew; Fuzell, Jack; Kumauchi, Masato; van Stokkum, Ivo; Groenhof, Gerrit; et al.

Journal or series: Biochemistry

ISSN: 1520-4995

eISSN: 0006-2960

Publication year: 2018

Volume: 57

Issue number: 1

Pages range: 1733-1747

Publisher: American Chemical Society

Publication country: United States

Publication language: English

DOI: https://doi.org/10.1021/acs.biochem.7b01114

Open Access: Publication channel is not openly available

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/57658


Photoactive yellow proteins (PYPs) make up a diverse class of blue-light-absorbing bacterial photoreceptors. Electronic excitation of the p-coumaric acid chromophore covalently bound within PYP results in triphasic quenching kinetics; however, the molecular basis of this behavior remains unresolved. Here we explore this question by examining the excitation-wavelength dependence of the photodynamics of the PYP from Halorhodospira halophila via a combined experimental and computational approach. The fluorescence quantum yield, steady-state fluorescence emission maximum, and cryotrapping spectra are demonstrated to depend on excitation wavelength. We also compare the femtosecond photodynamics in PYP at two excitation wavelengths (435 and 475 nm) with a dual-excitation-wavelength-interleaved pump–probe technique. Multicompartment global analysis of these data demonstrates that the excited-state photochemistry of PYP depends subtly, but convincingly, on excitation wavelength with similar kinetics with distinctly different spectral features, including a shifted ground-state beach and altered stimulated emission oscillator strengths and peak positions. Three models involving multiple excited states, vibrationally enhanced barrier crossing, and inhomogeneity are proposed to interpret the observed excitation-wavelength dependence of the data. Conformational heterogeneity was identified as the most probable model, which was supported with molecular mechanics simulations that identified two levels of inhomogeneity involving the orientation of the R52 residue and different hydrogen bonding networks with the p-coumaric acid chromophore. Quantum calculations were used to confirm that these inhomogeneities track to altered spectral properties consistent with the experimental results.

Free keywords: Photoactive Yellow Proteins

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Ministry reporting: Yes

Reporting Year: 2018

JUFO rating: 1

Last updated on 2020-18-10 at 18:45