scholarly journals A Favorable Path to Domain Separation in the Orange Carotenoid Protein

2022 ◽  
Author(s):  
Mahmoud Sharawy ◽  
Natalia B. Pigni ◽  
Eric R. May ◽  
José A. Gascón
Keyword(s):  
Orange Carotenoid Protein ◽  
Domain Separation

scholarly journals A Favorable Path to Domain Separation in the Orange Carotenoid Protein

2021 ◽  
Author(s):  
Mahmoud Sharawy ◽  
Natalia B. Pigni ◽  
Eric R. May ◽  
José A. Gascón
Keyword(s):  
Free Energy ◽  
Conformational Changes ◽  
Defense Mechanism ◽  
Optimization Methods ◽  
Free Energy Surface ◽  
Pathway Optimization ◽  
Orange Carotenoid Protein ◽  
Probable Path ◽  
Most Probable Path ◽  
Domain Separation

The Orange Carotenoid Protein (OCP) is responsible for nonphotochemical quenching (NPQ) in cyanobacteria, a defense mechanism against potentially damaging effects of excess light conditions. This soluble two-domain protein undergoes profound conformational changes upon photoactivation, involving translocation of the ketocarotenoid inside the cavity followed by domain separation. Domain separation is a critical step in the photocycle of OCP because it exposes the N-terminal domain (NTD) to perform quenching of the phycobilisomes. Many details regarding the mechanism and energetics of OCP domain separation remain unknown. In this work, we apply metadynamics to elucidate the protein rearrangements that lead to the active, domain-separated, form of OCP. We find that translocation of the ketocarotenoid canthaxanthin has a profound effect on the energetic landscape and that domain separation only becomes favorable following translocation. We further explore, characterize, and validate the free energy surface (FES) using equilibrium simulations initiated from different states on the FES. Through pathway optimization methods, we characterize the most probable path to domain separation and reveal the barriers along that pathway. We find that the free energy barriers are relatively small (<5 kcal/mol), but the overall estimated kinetic rate is consistent with experimental measurements (>1 ms). Overall, our results provide detailed information on the requirement for canthaxanthin translocation to precede domain separation and an energetically feasible pathway to dissociation.

scholarly journals A Favorable Path to Domain Separation in the Orange Carotenoid Protein

2021 ◽  
Author(s):  
Mahmoud Sharawy ◽  
Natalia B. Pigni ◽  
Eric R. May ◽  
José A. Gascón
Keyword(s):  
Orange Carotenoid Protein ◽  
Domain Separation

scholarly journals A Favorable Path to Domain Separation in the Orange Carotenoid Protein

2021 ◽  
Author(s):  
Mahmoud Sharawy ◽  
Natalia B. Pigni ◽  
Eric R. May ◽  
José A. Gascón
Keyword(s):  
Defense Mechanism ◽  
Protein Domains ◽  
Structural Rearrangement ◽  
Light Conditions ◽  
Structural Rearrangements ◽  
Fundamental Part ◽  
Activated State ◽  
Orange Carotenoid Protein ◽  
Standing Question ◽  
Domain Separation

In this work, we have modeled a fundamental part of the defense mechanism of Cyanobacteria against damaging effects of excess light conditions. This mechanism is part of the photoactivation cycle in the Orange Carotenoid Protein (OCP), which involves the separation of protein domains triggered by chromophore translocation. Using carefully designed metadynamics simulations, we have discovered the structural rearrangements along an energetically favorable pathway to the activated state. The structural rearrangement of OCP along its activation path has been a long-standing question, only answered now by our work.<br>

scholarly journals A Favorable Path to Domain Separation in the Orange Carotenoid Protein

2021 ◽  
Author(s):  
Mahmoud Sharawy ◽  
Natalia B. Pigni ◽  
Eric R. May ◽  
José A. Gascón
Keyword(s):  
Defense Mechanism ◽  
Protein Domains ◽  
Structural Rearrangement ◽  
Light Conditions ◽  
Structural Rearrangements ◽  
Fundamental Part ◽  
Activated State ◽  
Orange Carotenoid Protein ◽  
Standing Question ◽  
Domain Separation

In this work, we have modeled a fundamental part of the defense mechanism of Cyanobacteria against damaging effects of excess light conditions. This mechanism is part of the photoactivation cycle in the Orange Carotenoid Protein (OCP), which involves the separation of protein domains triggered by chromophore translocation. Using carefully designed metadynamics simulations, we have discovered the structural rearrangements along an energetically favorable pathway to the activated state. The structural rearrangement of OCP along its activation path has been a long-standing question, only answered now by our work.<br>

scholarly journals Structure of cyanobacterial phycobilisome core revealed by structural modeling and chemical cross-linking

2021 ◽  
Vol 7 (2) ◽  
pp. eaba5743
Author(s):  
Haijun Liu ◽  
Mengru M. Zhang ◽  
Daniel A. Weisz ◽  
Ming Cheng ◽  
Himadri B. Pakrasi ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Excitation Energy Transfer ◽  
Energy Coupling ◽  
Regulatory Elements ◽  
Photochemical Activity ◽  
Structural Basis ◽  
Bottom Surface ◽  
Cross Linking ◽  
Orange Carotenoid Protein ◽  
Chemical Cross Linking

In cyanobacteria and red algae, the structural basis dictating efficient excitation energy transfer from the phycobilisome (PBS) antenna complex to the reaction centers remains unclear. The PBS has several peripheral rods and a central core that binds to the thylakoid membrane, allowing energy coupling with photosystem II (PSII) and PSI. Here, we have combined chemical cross-linking mass spectrometry with homology modeling to propose a tricylindrical cyanobacterial PBS core structure. Our model reveals a side-view crossover configuration of the two basal cylinders, consolidating the essential roles of the anchoring domains composed of the ApcE PB loop and ApcD, which facilitate the energy transfer to PSII and PSI, respectively. The uneven bottom surface of the PBS core contrasts with the flat reducing side of PSII. The extra space between two basal cylinders and PSII provides increased accessibility for regulatory elements, e.g., orange carotenoid protein, which are required for modulating photochemical activity.

scholarly journals Carotenoids from Cyanobacteria: Biotechnological Potential and Optimization Strategies

Biomolecules ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 735
Author(s):  
Fernando Pagels ◽  
Vitor Vasconcelos ◽  
Ana Catarina Guedes
Keyword(s):  
Energy Dissipation ◽  
Industrial Production ◽  
Protein Complex ◽  
Biosynthetic Pathway ◽  
Environmentally Friendly ◽  
Potential Candidate ◽  
Biotechnological Potential ◽  
Photosynthetic Organisms ◽  
Orange Carotenoid Protein ◽  
Β Carotene

Carotenoids are tetraterpenoids molecules present in all photosynthetic organisms, responsible for better light-harvesting and energy dissipation in photosynthesis. In cyanobacteria, the biosynthetic pathway of carotenoids is well described, and apart from the more common compounds (e.g., β-carotene, zeaxanthin, and echinenone), specific carotenoids can also be found, such as myxoxanthophyll. Moreover, cyanobacteria have a protein complex called orange carotenoid protein (OCP) as a mechanism of photoprotection. Although cyanobacteria are not the organism of choice for the industrial production of carotenoids, the optimisation of their production and the evaluation of their bioactive capacity demonstrate that these organisms may indeed be a potential candidate for future pigment production in a more environmentally friendly and sustainable approach of biorefinery. Carotenoids-rich extracts are described as antioxidant, anti-inflammatory, and anti-tumoral agents and are proposed for feed and cosmetical industries. Thus, several strategies for the optimisation of a cyanobacteria-based bioprocess for the obtention of pigments were described. This review aims to give an overview of carotenoids from cyanobacteria not only in terms of their chemistry but also in terms of their biotechnological applicability and the advances and the challenges in the production of such compounds.

scholarly journals Photoactivation Mechanism, Timing of Protein Secondary Structure Dynamics and Carotenoid Translocation in the Orange Carotenoid Protein

2018 ◽  
Vol 141 (1) ◽  
pp. 520-530 ◽  
Author(s):  
Patrick E. Konold ◽  
Ivo H. M. van Stokkum ◽  
Fernando Muzzopappa ◽  
Adjélé Wilson ◽  
Marie-Louise Groot ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Protein Secondary Structure ◽  
Structure Dynamics ◽  
Orange Carotenoid Protein

scholarly journals Structural Rearrangements in the C-Terminal Domain Homolog of Orange Carotenoid Protein are Crucial for Carotenoid Transfer

2019 ◽  
Vol 116 (3) ◽  
pp. 47a
Author(s):  
Dvir Harris ◽  
Adjele Wilson ◽  
Fernando Muzzopappa ◽  
Nikolai N. Sluchanko ◽  
Thomas Friedrich ◽  
...  
Keyword(s):  
Structural Rearrangements ◽  
Terminal Domain ◽  
Orange Carotenoid Protein

Domain separation by means of sign changing eigenfunctions ofp-laplacians

2001 ◽  
Vol 79 (3-4) ◽  
pp. 483-501 ◽  
Author(s):  
Herbert Gajewski ◽  
Klaus Gartner
Keyword(s):  
Domain Separation
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