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Title: Observation of conformational dynamics in single light-harvesting proteins from cryptophyte algae

Journal Article · · Journal of Chemical Physics
DOI:https://doi.org/10.1063/5.0095763· OSTI ID:1908531

Photosynthetic organisms use pigment–protein complexes to capture the sunlight that powers most life on earth. Within these complexes, the position of the embedded pigments is all optimized for light harvesting. At the same time, the protein scaffold undergoes thermal fluctuations that vary the structure, and, thus, photophysics, of the complexes. While these variations are averaged out in ensemble measurements, single-molecule spectroscopy provides the ability to probe these conformational changes. We used single-molecule fluorescence spectroscopy to identify the photophysical substates reflective of distinct conformations and the associated conformational dynamics in phycoerythrin 545 (PE545), a pigment–protein complex from cryptophyte algae. Rapid switching between photophysical states was observed, indicating that ensemble measurements average over a conformational equilibrium. A highly quenched conformation was also identified, and its population increased under high light. This discovery establishes that PE545 has the characteristics to serve as a photoprotective site. Finally, unlike homologous proteins from the evolutionarily related cyanobacteria and red algae, quenching was not observed upon photobleaching, which may allow for robust photophysics without the need for rapid repair or replacement machinery. Collectively, these observations establish the presence of a rich and robust set of conformational states of PE545. Cryptophytes exhibit particularly diverse energetics owing to the variety of microenvironments in which they survive, and the conformational states and dynamics reported here may provide photophysical flexibility that contributes to their remarkable ability to flourish under diverse conditions.

Research Organization:
Princeton Univ., NJ (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Organization:
USDOE Office of Science (SC) Basic Energy Sciences (BES); USDOE
Grant/Contract Number:
SC0019370
OSTI ID:
1908531
Alternate ID(s):
OSTI ID: 1876660
Journal Information:
Journal of Chemical Physics, Vol. 157, Issue 3; ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English

References (46)

How Energy Funnels from the Phycoerythrin Antenna Complex to Photosystem I and Photosystem II in Cryptophyte Rhodomonas CS24 Cells
  • van der Weij-De Wit, Chantal D.; Doust, Alexander B.; van Stokkum, Ivo H. M.
  • The Journal of Physical Chemistry B, Vol. 110, Issue 49 https://doi.org/10.1021/jp061546w
journal November 2006
Light Harvesting by Phycobilisomes journal June 1985
Structural dynamics of potassium-channel gating revealed by single-molecule FRET journal December 2015
Unique Location of the Phycobiliprotein Light-Harvesting Pigment in the Cryptophyceae journal September 1989
Developing a Structure–Function Model for the Cryptophyte Phycoerythrin 545 Using Ultrahigh Resolution Crystallography and Ultrafast Laser Spectroscopy journal November 2004
Dissecting pigment architecture of individual photosynthetic antenna complexes in solution journal October 2015
Excitation-energy redistribution in the cryptomonad alga Cryptomonas ovata journal June 1987
Chloroplast Structure of the Cryptophyceae journal February 1971
Application of spectrally resolved fluorescence induction to study light-induced nonphotochemical quenching in algae journal March 2018
Toward dynamic structural biology: Two decades of single-molecule Förster resonance energy transfer journal January 2018
Single-Molecule Identification of Quenched and Unquenched States of LHCII journal February 2015
Lifetime and Spectrally Resolved Characterization of the Photodynamics of Single Fluorophores in Solution Using the Anti-Brownian Electrokinetic Trap journal November 2012
Initial Transcription by RNA Polymerase Proceeds Through a DNA-Scrunching Mechanism journal November 2006
Generation and identification of the transient intermediates of allophycocyanin by laser photolytic and pulse radiolytic techniques journal January 2001
Switching an Individual Phycobilisome Off and On journal April 2018
Proteomic analysis of the phycobiliprotein antenna of the cryptophyte alga Guillardia theta cultured under different light intensities journal May 2017
Detection of Intensity Change Points in Time-Resolved Single-Molecule Measurements journal January 2005
Photoblinking of Rhodamine 6G in Poly(vinyl alcohol):  Radical Dark State Formed through the Triplet journal August 2003
Single-molecule spectroscopy of LHCSR1 protein dynamics identifies two distinct states responsible for multi-timescale photosynthetic photoprotection journal July 2017
Evolution of a light-harvesting protein by addition of new subunits and rearrangement of conserved elements: Crystal structure of a cryptophyte phycoerythrin at 1.63-A resolution journal August 1999
Spectral Heterogeneity in Single Light-harvesting Chlorosomes from Green Sulfur Photosynthetic Bacterium Chlorobium tepidum¶ journal April 2002
The role of far-red spectral states in the energy regulation of phycobilisomes journal April 2019
Charge transfer states in phycobilisomes journal July 2020
Kinetics of allophycocyanin's trimer-monomer equilibrium journal January 1987
Watching conformational- and photodynamics of single fluorescent proteins in solution journal January 2010
Fluorescence Spectroscopy, Exciton Dynamics, and Photochemistry of Single Allophycocyanin Trimers journal December 1998
Fluorescence and photobleaching dynamics of single light-harvesting complexes journal September 1997
Photoprotective, excited-state quenching mechanisms in diverse photosynthetic organisms journal January 2018
Enzymatic Oxygen Scavenging for Photostability without pH Drop in Single-Molecule Experiments journal June 2012
Phycoerythrin 545:  Monomers, Energy Migration, Bilin Topography, and Monomer/Dimer Equilibrium journal January 1998
Cooperative Subunit Refolding of a Light‐Harvesting Protein through a Self‐Chaperone Mechanism journal February 2017
Fluorescence Spectral Fluctuations of Single LH2 Complexes from Rhodopseudomonas acidophila Strain 10050 journal April 2004
Energy Flow in the Cryptophyte PE545 Antenna Is Directed by Bilin Pigment Conformation journal October 2012
Non-Photochemical Quenching in Cryptophyte Alga Rhodomonas salina Is Located in Chlorophyll a/c Antennae journal January 2012
Presence of state transitions in the cryptophyte alga Guillardia theta journal August 2015
Function, regulation and distribution of IsiA, a membrane-bound chlorophyll a-antenna protein in cyanobacteria journal January 2018
Immobility of phycobilins in the thylakoid lumen of a cryptophyte suggests that protein diffusion in the lumen is very restricted journal January 2009
An Oxygen Scavenging System for Improvement of Dye Stability in Single-Molecule Fluorescence Experiments journal March 2008
Controlling Light Harvesting with Light journal September 2016
Phycocyanin: One Complex, Two States, Two Functions journal March 2018
High light stress and the one-helix LHC-like proteins of the cryptophyte Guillardia theta journal July 2011
Single-Molecule Fluorescence Spectroscopy of Photosynthetic Systems journal March 2016
Direct single-molecule measurements of phycocyanobilin photophysics in monomeric C-phycocyanin journal August 2017
Excitation Dynamics in Phycoerythrin 545: Modeling of Steady-State Spectra and Transient Absorption with Modified Redfield Theory journal July 2010
Probing Single Biomolecules in Solution Using the Anti-Brownian Electrokinetic (ABEL) Trap journal March 2012
Evolution of the Phycobiliproteins journal April 1995