<i>In silico</i> model of an antenna of a phycobilisome and energy transfer rates determination by theoretical Förster approach

Figueroa, Maximiliano; Martínez‐Oyanedel, José; Matamala, Adelio R.; Dagnino‐Leone, Jorge; Mella, Claudia; Fritz, Rubén A.; Sepúlveda-Ugarte, José; Bunster, Marta

doi:10.1002/pro.2176

Cited by 11 publications

(10 citation statements)

References 39 publications

(45 reference statements)

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“…At this distance, energy transfer is typically associated with the FRET model (51). The distance of 34 Å between the closest chromophores of PC and APC hexamers in the model we present here is in agreement with previous studies of energy transfer in PCs higher assemblies and the distances between pairs of chromophores, which energy most likely travels through (8,52,53). Although one might assume that because of the relatively long distance between the terminal rod emitter and the initial core acceptor, energy transfer would be concomitantly slow.…”

Section: Discussionsupporting

confidence: 91%

Investigation of Phycobilisome Subunit Interaction Interfaces by Coupled Cross-linking and Mass Spectrometry

Tal

Trabelcy

Gerchman

et al. 2014

Journal of Biological Chemistry

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Background:The phycobilisome is assembled from many subunits, but the entire structure has not been determined. Results: Coupled cross-linking/MS revealed neighboring residues within the interfaces between subunits. Conclusion: The rods completely cover the core cylinders and are not in a staggered assembly form. Significance: Energy transfer from rods to cores overcomes a jump of over 30 Å without loss of efficiency.

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Section: Discussionsupporting

confidence: 91%

Investigation of Phycobilisome Subunit Interaction Interfaces by Coupled Cross-linking and Mass Spectrometry

Tal

Trabelcy

Gerchman

et al. 2014

Journal of Biological Chemistry

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“…Electron microscopy : The micrographs were obtained in a Philips Tecnai 12 Bio Twin EM (120kv) at the Pontificia Universidad Católica de Chile facility, using the methodology described [ 23 ] for complete phycobilisomes.…”

Section: Methodsmentioning

confidence: 99%

“…composition, structure or component interactions of the PBS provides the frame for the high efficiency of the energy transfer towards PSII. Until now, the structure of PE and PC from Gch has been reported previously by our group [ 21 , 22 ], as well as information about interaction between hexamers in a rod and its role in the function of energy transfer [ 23 ]. In this article, we report i) the three cylinders nature of the core of the PBS in Gch , ii) the sequences of the subunits components of the core, iii) the sequence analysis and iv) the X-ray structure for Allophycocyanin from Gch (αβ) 3 .…”

Section: Introductionmentioning

confidence: 99%

Structural models of the different trimers present in the core of phycobilisomes from Gracilaria chilensis based on crystal structures and sequences

et al. 2017

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Phycobilisomes (PBS) are accessory light harvesting protein complexes that directionally transfer energy towards photosystems. Phycobilisomes are organized in a central core and rods radiating from it. Components of phycobilisomes in Gracilaria chilensis (Gch) are Phycobiliproteins (PBPs), Phycoerythrin (PE), and Phycocyanin (PC) in the rods, while Allophycocyanin (APC) is found in the core, and linker proteins (L). The function of such complexes depends on the structure of each component and their interaction. The core of PBS from cyanobacteria is mainly composed by cylinders of trimers of α and β subunits forming heterodimers of Allophycocyanin, and other components of the core including subunits αII and β18. As for the linkers, Linker core (LC) and Linker core membrane (LCM) are essential for the final emission towards photoreaction centers. Since we have previously focused our studies on the rods of the PBS, in the present article we investigated the components of the core in the phycobilisome from the eukaryotic algae, Gracilaria chilensis and their organization into trimers. Transmission electron microscopy provided the information for a three cylinders core, while the three dimensional structure of Allophycocyanin purified from Gch was determined by X-ray diffraction method and the biological unit was determined as a trimer by size exclusion chromatography. The protein sequences of all the components of the core were obtained by sequencing the corresponding genes and their expression confirmed by transcriptomic analysis. These subunits have seldom been reported in red algae, but not in Gracilaria chilensis. The subunits not present in the crystallographic structure were modeled to build the different composition of trimers. This article proposes structural models for the different types of trimers present in the core of phycobilisomes of Gch as a first step towards the final model for energy transfer in this system.

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“…The lack ofspecific atomic information about γ subunits associated to PE, makes difficult to incorporate these linkers into our energy transfer model in PBS from the red alga G . ch [ 17 ]. Therefore, although we could identify both γ subunits, in this work we present the sequence and spectroscopic information on γ 33 .…”

Section: Introductionmentioning

confidence: 99%

The γ33 subunit of R-phycoerythrin from Gracilaria chilensis has a typical double linked phycourobilin similar to γ subunit

et al. 2018

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Phycobilisomes (PBS) are accessory light harvesting protein complexes formed mainly by phycobiliproteins (PBPs). The PBPs absorb light that is efficiently transferred to Photosystems due to chromophores covalently bound to specific cysteine residues. Besides phycobiliproteins (PE), the PBS contains linker proteins responsible for assembly and stabilization of the whole complex and the tuning of energy transfer steps between chromophores. The linker (γ33) from Gracilaria chilensis, is a chromophorylated rod linker associated to (αβ)6 hexamers of R-phycoerythrin (R-PE). Its role in the energy transfer process is not clear yet. Structural studies as well as the composition and location of the chromophores are essential to understand their involvement in the energy transfer process in PBS. To achieve this, the coding gene of γ33 was cloned and sequenced. The sequence was analyzed by informatics tools, to obtain preliminary information which leaded the next experiments. The protein was purified from R-phycoerythrin, and the sequence confirmed by mass spectrometry. The coding sequence analysis revealed a protein of 318 aminoacid residues containing a chloroplastidial transit peptide (cTP) of 39 aminoacids at the N-terminus. The conservation of cysteines revealed possible chromophorylation sites. Using α and β R-PE subunits as spectroscopic probes in denaturation assays, we deduced a double bonded phycourobilin (PUB) on γ33 subunit that were confirmed between Cys62 and Cys73 (DL-PUB62/73) by mass spectrometry. The cysteines involved in the double link are located in a helical region, in a conformation that reminds the position of the DL-PUB50/61 in the β subunit of R-PE. The position of single linked PUB at Cys95 and a single linked PEB at Cys172 were also confirmed. Spectroscopic studies show the presence of both types of chromophores and that there are not energy transfer by FRET among them.

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In silico model of an antenna of a phycobilisome and energy transfer rates determination by theoretical Förster approach

Cited by 11 publications

References 39 publications

Investigation of Phycobilisome Subunit Interaction Interfaces by Coupled Cross-linking and Mass Spectrometry

Investigation of Phycobilisome Subunit Interaction Interfaces by Coupled Cross-linking and Mass Spectrometry

Structural models of the different trimers present in the core of phycobilisomes from Gracilaria chilensis based on crystal structures and sequences

The γ33 subunit of R-phycoerythrin from Gracilaria chilensis has a typical double linked phycourobilin similar to γ subunit

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