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Evidence of Simultaneous Spectral Hole Burning Involving Two Tiers of the Protein Energy Landscape in Cytochrome b6f.

Author(s): Shafiei G, Levenberg A, Lujan MA, Picorel R, Zazubovich V

J Phys Chem B. 2019 Dec 12;: Authors: Shafiei G, Levenberg A, Lujan MA, Picorel R, Zazubovich V

Article GUID: 31763829
Conformational Changes in Pigment-Protein Complexes at Low Temperatures-Spectral Memory and a Possibility of Cooperative Effects.

Author(s): Najafi M, Herascu N, Shafiei G, Picorel R, Zazubovich V

J Phys Chem B. 2015 Jun 11;119(23):6930-40 Authors: Najafi M, Herascu N, Shafiei G, Picorel R, Zazubovich V

Article GUID: 25985255
Probing Energy Landscapes of Cytochrome b6f with Spectral Hole Burning: Effects of Deuterated Solvent and Detergent.

Author(s): Levenberg A, Shafiei G, Lujan MA, Giannacopoulos S, Picorel R, Zazubovich V

J Phys Chem B. 2017 10 26;121(42):9848-9858 Authors: Levenberg A, Shafiei G, Lujan MA, Giannacopoulos S, Picorel R, Zazubovich V

Article GUID: 28956922
Spectral Hole Burning in Cyanobacterial Photosystem I with P700 in Oxidized and Neutral States.

Author(s): Herascu N, Hunter MS, Shafiei G, Najafi M, Johnson TW, Fromme P, Zazubovich V

J Phys Chem B. 2016;120(40):10483-10495 Authors: Herascu N, Hunter MS, Shafiei G, Najafi M, Johnson TW, Fromme P, Zazubovich V

Article GUID: 27661089
Title:Spectral Hole Burning in Cyanobacterial Photosystem I with P700 in Oxidized and Neutral States.
Authors:Herascu N,  Hunter MS,  Shafiei G,  Najafi M,  Johnson TW,  Fromme P,  Zazubovich V
Link:https://www.ncbi.nlm.nih.gov/pubmed/27661089?dopt=Abstract
Category:J Phys Chem B
PMID:27661089
Dept Affiliation: CHEMBIOCHEM
1 Department of Physics, Concordia University , 7141 Sherbrooke Street West, Montreal, H4B 1R4, Quebec, Canada.
2 Department of Chemistry and Biochemistry, Arizona State University , Tempe, Arizona, United States.
3 Department of Chemistry, Susquehanna University , Selinsgrove, Pennsylvania, United States.

Description:

Spectral Hole Burning in Cyanobacterial Photosystem I with P700 in Oxidized and Neutral States.

J Phys Chem B. 2016;120(40):10483-10495

Authors: Herascu N, Hunter MS, Shafiei G, Najafi M, Johnson TW, Fromme P, Zazubovich V

Abstract

We explored the rich satellite hole structures emerging as a result of spectral hole burning in cyanobacterial photosystem I (PSI) and demonstrated that hole burning properties of PSI, particularly at high resolution, are strongly affected by the oxidation state of the primary donor P700, as P700+ effectively quenches the excitations of the lowest-energy antenna states responsible for fluorescence. Obtaining better control of this variable will be crucial for high-resolution ensemble experiments on protein energy landscapes in PSI. The separate nonphotochemical spectral hole burning (NPHB) signatures of various red antenna states were obtained, allowing for additional constraints on excitonic structure-based calculations. Preliminary evidence is presented for an additional red state of PSI of T. elongatus peaked at 712.6 nm, distinct from previously reported C708 and C715 states and possibly involving chlorophyll B15. Excitation at wavelengths as long as 800 nm results in charge separation at cryogenic temperatures in PSI also in Synechocystis sp. PCC 6803. Both the "P700+ minus P700" holes and nonphotochemical spectral holes were subjected to thermocycling. The distribution of barriers manifesting in recovery of the "P700+ minus P700" signature contains two components in sample-dependent proportions, likely reflecting the percentages of FA and FB clusters being successfully prereduced before the optical experiment. The barrier distribution for the recovery of the lower-energy nonphotochemical spectral holes resembles those observed for other pigment-protein complexes, suggesting similar structural elements are responsible for NPHB. Higher-energy components exhibit evidence of "domino effects" such as shifts of certain bands persisting past the lower-energy hole recovery. Thus, conformational changes triggered by excitation of one pigment likely can affect multiple pigments in this tightly packed system.

PMID: 27661089 [PubMed]