An Unexpected Water Channel in the Light-Harvesting Complex of a Diatom: Implications for the Switch between Light Harvesting and Photoprotection DOI Creative Commons
Vangelis Daskalakis, Sayan Maity, Ulrich Kleinekathöfer

et al.

ACS Physical Chemistry Au, Journal Year: 2024, Volume and Issue: 5(1), P. 47 - 61

Published: Aug. 21, 2024

Many important processes in cells depend on the transfer of protons through water wires embedded transmembrane proteins. Herein, we have performed more than 55 μs all-atom simulations light-harvesting complex a diatom, i.e., fucoxanthin and chlorophyll a/c binding protein (FCP) from marine diatom Phaeodactylum tricornutum. Diatoms are unique models to study natural photosynthesis as they exert an efficient machinery with robust pH-dependent photoprotective mechanism. The present reports dynamics FCP monomer, dimer, tetramer at varying pH values. Surprisingly, identified low channel across that selectively hydrates protonates acrylate Chl-c2 pigment located middle membrane. These results further supported by QM/MM calculations steered MD proton dynamics. It is shown hopping events between lumenal stromal sides membrane observed highly disfavored. This hindrance due presence residues Arg31 Lys82 close acrylate, along hydronium desolvation penalty shows similarities conductance aquaporins. Furthermore, provide strong evidence this governing transition states major P.

Language: Английский

Bioinspired Water Preorganization in Confined Space for Efficient Water Oxidation Catalysis in Metallosupramolecular Ruthenium Architectures DOI Creative Commons
Niklas Noll, Frank Würthner

Accounts of Chemical Research, Journal Year: 2024, Volume and Issue: 57(10), P. 1538 - 1549

Published: May 6, 2024

ConspectusNature has established a sustainable way to maintain aerobic life on earth by inventing one of the most sophisticated biological processes, namely, natural photosynthesis, which delivers us with organic matter and molecular oxygen derived from two abundant resources sunlight water. The thermodynamically demanding photosynthetic water splitting is catalyzed oxygen-evolving complex in photosystem II (OEC-PSII), comprises distorted tetramanganese–calcium cluster (CaMn4O5) as catalytic core. As an ubiquitous concept for fine-tuning regulating reactivity active site metalloenzymes, surrounding protein domain creates environment that promotes substrate preorganization through secondary, noncovalent interactions such hydrogen bonding or electrostatic interactions. Based high-resolution X-ray structure PSII, several channels were identified near site, are filled extensive hydrogen-bonding networks preorganized molecules, connecting OEC surface. integral part outer coordination sphere these control product delivery, carefully regulate proton flow promoting pivotal proton-coupled electron transfer simultaneously stabilize short-lived oxidized intermediates, thus highlighting importance ordered network remarkable efficiency OEC.Transferring this nature engineering artificial metal catalysts fuel production fostered fascinating field metallosupramolecular chemistry generating defined cavities conceptually mimic enzymatic pockets. However, application supramolecular approaches generate oxidation remained scarce prior our initial reports, since design strategies efficient activation molecules confined nanoenvironments lacking. In Account, we describe research efforts combining state-of-the art Ru(bda) framework structurally programmed ditopic ligands guide process assemblies spatial proximity. We will elucidate governing factors quality multinuclear varying sizes geometries obtain high-performance, state-of-the-art catalysts. Pushing boundaries catalyst design, embedding single Ru center into well-defined pocket enabled front encoded basic recognition resulting high rates comparable those counterpart OEC-PSII.To fully explore their potential solar devices, suitability was demonstrated under (electro)chemical photocatalytic conditions. addition, testing limits structural diversity allowed fabrication self-assembled linear oligomers novel materials long-range covalent (COF) recyclable long-term stable solid-state future applications.

Language: Английский

Citations

7
Structure of the intact C2S2-type Photosystem II-LHCII supercomplex from Arabidopsis thaliana at 2.44 Å DOI Creative Commons
Johannes Messinger, Jack Forsman, André T. Graça

et al.

Research Square (Research Square), Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 9, 2025

Abstract Photosystem II (PSII) is a large membrane-bound protein complex that essential for oxygenic photosynthesis in plants and cyanobacteria. While there are several high-resolution structures of PS from cyanobacteria, very few have been reported higher plants. Here, we present the first structure an intact active Arabidopsis thaliana at resolution 2.44 Å, which to date represents highest any land plant. The improved allowed modeling cofactors not previously seen plant structures. Importantly, were able identify many water molecules within structure, including waters around water-splitting manganese cluster, bottleneck regions water/proton channels, near non-heme iron on acceptor side. Structural differences between cyanobacterial discussed.

Language: Английский

Citations

0
Structure of a mutated photosystem II complex reveals changes to the hydrogen-bonding network that affect proton egress during O–O bond formation DOI Creative Commons
David A. Flesher, Jieun Shin, Richard J. Debus

et al.

Journal of Biological Chemistry, Journal Year: 2025, Volume and Issue: unknown, P. 108272 - 108272

Published: Feb. 1, 2025

Photosystem II (PSII) is the water-splitting enzyme of oxygenic photosynthesis. Using light energy, PSII catalytically oxidizes two water molecules to fuel downstream metabolism, forming an O-O bond and releasing O2 as a byproduct. The reaction mechanism requires strategic removal four protons via conserved hydrogen-bonding networks, but these pathways remain poorly understood. Site-directed mutagenesis has been used study role specific side chains, such Lys317 D2 subunit. Previous studies showed that D2-Lys317Ala substitution, which abolishes flexible -NH3+ group, resulted in delayed release kinetics diminished catalytic turnover, suggesting crucial facilitating proton egress. Here, we investigated this egress pathway by determining cryo-EM structure containing substitution at resolution 1.97 Å. We observed new fill space previously occupied Lys317, waters lack water-protein interactions, leading heterogeneity suboptimal hydrogen bonding. hypothesize negatively contribute existing network increase entropic barrier for transfer. Additionally, chloride ion (Cl1), associated with unexpectedly maintained PSII. However, unlike wild-type, Cl1 no measured effect on oxygen-evolution rates This suggests dependent amino group. These findings provide insight into through channel.

Language: Английский

Citations

0
Independent Mutation of Two Bridging Carboxylate Ligands Stabilizes Alternate Conformers of the Photosynthetic O2-Evolving Mn4CaO5 Cluster in Photosystem II DOI
Richard J. Debus, Paul H. Oyala

The Journal of Physical Chemistry B, Journal Year: 2024, Volume and Issue: 128(16), P. 3870 - 3884

Published: April 11, 2024

The O2-evolving Mn4CaO5 cluster in photosystem II is ligated by six carboxylate residues. One of these D170 the D1 subunit. This bridges between one Mn ion (Mn4) and Ca ion. A second ligand D342 two ions (Mn1 Mn2). are located on opposite sides cluster. Recently, it was shown that D170E mutation perturbs both intricate networks H-bonds surround equilibrium different conformers its lower oxidation states, S1 S2, while still supporting O2 evolution at approximately 50% rate wild type. In this study, we show D342E produces much same alterations to cluster's FTIR EPR spectra as D170E, 20% Furthermore, double mutation, + D342E, behaves similarly single mutations. We conclude alters S2 states manner H-bond a similar fashion. identification metal whose influences without eliminating evolution. finding has implications for our understanding mechanism formation terms catalytically active/inactive conformations states.

Language: Английский

Citations

1
An Unexpected Water Channel in the Light-Harvesting Complex of a Diatom: Implications for the Switch between Light Harvesting and Photoprotection DOI Creative Commons
Vangelis Daskalakis, Sayan Maity, Ulrich Kleinekathöfer

et al.

ACS Physical Chemistry Au, Journal Year: 2024, Volume and Issue: 5(1), P. 47 - 61

Published: Aug. 21, 2024

Many important processes in cells depend on the transfer of protons through water wires embedded transmembrane proteins. Herein, we have performed more than 55 μs all-atom simulations light-harvesting complex a diatom, i.e., fucoxanthin and chlorophyll a/c binding protein (FCP) from marine diatom Phaeodactylum tricornutum. Diatoms are unique models to study natural photosynthesis as they exert an efficient machinery with robust pH-dependent photoprotective mechanism. The present reports dynamics FCP monomer, dimer, tetramer at varying pH values. Surprisingly, identified low channel across that selectively hydrates protonates acrylate Chl-c2 pigment located middle membrane. These results further supported by QM/MM calculations steered MD proton dynamics. It is shown hopping events between lumenal stromal sides membrane observed highly disfavored. This hindrance due presence residues Arg31 Lys82 close acrylate, along hydronium desolvation penalty shows similarities conductance aquaporins. Furthermore, provide strong evidence this governing transition states major P.

Language: Английский

Citations

1