scholarly journals Structure, Dynamics, and Function in the Major Light-Harvesting Complex of Photosystem II

2012 ◽  
Vol 65 (6) ◽  
pp. 583 ◽  
Author(s):  
Gabriela S. Schlau-Cohen ◽  
Graham R. Fleming
Keyword(s):  
Excited State ◽  
Photosystem Ii ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Electronic Spectroscopy ◽  
Emergent Properties ◽  
Light Harvesting Complex ◽  
Natural Systems ◽  
Harvesting Systems ◽  
And Function

In natural light-harvesting systems, pigment-protein complexes (PPC) convert sunlight to chemical energy with near unity quantum efficiency. PPCs exhibit emergent properties that cannot be simply extrapolated from knowledge of their component parts. In this Perspective, we examine the design principles of PPCs, focussing on the major light-harvesting complex of Photosystem II (LHCII), the most abundant PPC in green plants. Studies using two-dimensional electronic spectroscopy (2DES) provide an incisive tool to probe the electronic, energetic, and spatial landscapes that enable the efficiency observed in photosynthetic light-harvesting. Using the information about energy transfer pathways, quantum effects, and excited state geometry contained within 2D spectra, the excited state properties can be linked back to the molecular structure. This understanding of the structure-function relationships of natural systems constitutes a step towards a blueprint for the construction of artificial light-harvesting devices that can reproduce the efficacy of natural systems.

scholarly journals Dissecting pigment architecture of individual photosynthetic antenna complexes in solution

2015 ◽  
Vol 112 (45) ◽  
pp. 13880-13885 ◽  
Author(s):  
Quan Wang ◽  
W. E. Moerner
Keyword(s):  
Single Molecule ◽  
Light Harvesting ◽  
Fluorescent Proteins ◽  
Protein Complexes ◽  
Photophysical Properties ◽  
Critical Role ◽  
Photosynthetic Pigment ◽  
Emergent Properties ◽  
Aqueous Environment ◽  
Harvesting Systems

Oligomerization plays a critical role in shaping the light-harvesting properties of many photosynthetic pigment−protein complexes, but a detailed understanding of this process at the level of individual pigments is still lacking. To study the effects of oligomerization, we designed a single-molecule approach to probe the photophysical properties of individual pigment sites as a function of protein assembly state. Our method, based on the principles of anti-Brownian electrokinetic trapping of single fluorescent proteins, step-wise photobleaching, and multiparameter spectroscopy, allows pigment-specific spectroscopic information on single multipigment antennae to be recorded in a nonperturbative aqueous environment with unprecedented detail. We focus on the monomer-to-trimer transformation of allophycocyanin (APC), an important antenna protein in cyanobacteria. Our data reveal that the two chemically identical pigments in APC have different roles. One (α) is the functional pigment that red-shifts its spectral properties upon trimer formation, whereas the other (β) is a “protective” pigment that persistently quenches the excited state of α in the prefunctional, monomer state of the protein. These results show how subtleties in pigment organization give rise to functionally important aspects of energy transfer and photoprotection in antenna complexes. The method developed here should find immediate application in understanding the emergent properties of other natural and artificial light-harvesting systems.

Absence of the major light-harvesting antenna proteins alters the redox properties of photosystem II reaction centres in the chlorina F2 mutant of barley

2009 ◽  
Vol 87 (4) ◽  
pp. 557-566 ◽  
Author(s):  
Marianna Krol ◽  
Alexander G. Ivanov ◽  
Isabelle Booij-James ◽  
Autar K. Mattoo ◽  
P. V. Sane ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Light Harvesting ◽  
Redox Properties ◽  
Reaction Centre ◽  
Light Harvesting Complex ◽  
Reaction Centres ◽  
D1 Polypeptide ◽  
And Function

Although the chlorina F2 mutant of barley specifically exhibits reduced levels of the major light-harvesting polypeptides associated with photosystem II (PSII), thermoluminescence measurements of photosystem reaction centre photochemistry revealed that S2/S3Q B– charge recombinations were shifted to lower temperatures, while the characteristic peak of S2Q A– charge recombinations was shifted to higher temperatures compared with wild-type (WT) barley. Thus, we show that the absence of the major light-harvesting polypeptides affects the redox properties of PSII reaction centres. Radiolabeling studies in vivo and in vitro with [32P]orthophosphate or [γ-32P]ATP, respectively, demonstrated that the D1 PSII reaction centre polypeptide is phosphorylated in both the WT and the F2 mutant. In contrast with the radiolabeling results, phosphorylation of D1 and other PSII proteins, although detected in WT barley, was ambiguous in the F2 mutant when the phosphothreonine antibody method of detection was used. Thus, caution must be exercised in the use of commercially available phosphothreonine antibodies to estimate thylakoid polypeptide phosphorylation. Furthermore, in membrano, the D1 polypeptide of the F2 mutant was less susceptible to trypsin treatment than that of WT barley. The role of the light-harvesting complex in modulating the structure and function of the D1 polypeptide of PSII reaction centers is discussed.

scholarly journals Structure of the stress-related LHCSR1 complex determined by an integrated computational strategy

2021 ◽  
Author(s):  
Ingrid Guarnetti Prandi ◽  
Vladislav Sláma ◽  
Cristina Pecorilla ◽  
Lorenzo Cupellini ◽  
Benedetta Mennucci
Keyword(s):  
Structural Model ◽  
Light Harvesting ◽  
Structural Information ◽  
Protein Complexes ◽  
Complex Stress ◽  
Main Function ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Pigment Protein Complexes ◽  
Computational Strategy

Light-harvesting complexes (LHCs) are pigment-protein complexes whose main function is to capture sunlight and transfer the energy to reaction centers of photosystems. In response to varying light conditions, LH complexes also play photoregulation and photoprotection roles. In algae and mosses, a sub-family of LHCs, Light-Harvesting complex stress related (LHCSR), is responsible for photoprotective quenching. Despite their functional and evolutionary importance, no direct structural information on LHCSRs is available that can explain their unique properties. In this work we propose a structural model of LHCSR1 from the moss P. Patens, obtained through an integrated computational strategy that combines homology modeling, molecular dynamics, and multiscale quantum chemical calculations. The model is validated by reproducing the spectral properties of LHCSR1. Our model reveals the structural specificity of LHCSR1, as compared with the CP29 LH complex, and poses the basis for understanding photoprotective quenching in mosses.

scholarly journals Solving structure in the CP29 light harvesting complex with polarization-phased 2D electronic spectroscopy

2011 ◽  
Vol 108 (10) ◽  
pp. 3848-3853 ◽  
Author(s):  
N. S. Ginsberg ◽  
J. A. Davis ◽  
M. Ballottari ◽  
Y.-C. Cheng ◽  
R. Bassi ◽  
...  
Keyword(s):  
Light Harvesting ◽  
Electronic Spectroscopy ◽  
Light Harvesting Complex
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