The structure at 2 Å resolution of Phycocyanin from Gracilaria chilensis and the energy transfer network in a PC–PC complex

Contreras‐Martel, Carlos; Matamala, Adelio R.; Bruna, Carola; Poo-Caamaño, German; Almonacid, Daniel E.; Figueroa, Maximiliano; Martínez‐Oyanedel, José; Bunster, Marta

doi:10.1016/j.bpc.2006.09.014

Cited by 45 publications

(22 citation statements)

References 44 publications

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“…The hexamers present a ring-like shape that allows them to pile up to form the rod. The three-dimensional structures of PE (PDB code: 1eyx) 4 and PC (PDB code: 2vb8) 5 from this algae have been determined previously in our group, and the structure of both proteins is shown in Figure 1(B,C), respectively. Table I 3,6 shows their chromophore composition and the main spectroscopic absorption and emission wavelengths.…”

Section: Introductionmentioning

confidence: 86%

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

Figueroa¹,

Martínez‐Oyanedel²,

Matamala³

et al. 2012

Protein Science

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Energy transfer (ET) in phycobilisomes, a macrocomplex of phycobiliproteins and linker proteins, is a process that is difficult to understand completely. A model for a rod composed of two hexamers of Phycocyanin and two hexamers of Phycoerythrin was built using an in silico approach and the three-dimensional structures of both phycobiliproteins from Gracilaria chilensis. The model was characterized and showed 125 Å wide and 230 Å high, which agree with the dimensions of a piling of four hexamers as observed in the images of subcomplexes of phycobilisomes obtained by transmission electron microscopy. ET rates between every pair of chromophores in the model were calculated using the F€ orster approach, and the fastest rates were selected to draw preferential ET pathways along the rod. Every path indicates that the ET is funneled toward the chromophores located at Cysteines 82 in Phycoerythrin and 84 in Phycocyanin. The chromophores that face the exterior of the rod are phycoerythrobilins, and they also show a preferential ET toward the chromophores located at the center of the rod. The values calculated, in general, agree with the experimental data reported previously, which validates the use of this experimental approach.

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Section: Introductionmentioning

confidence: 86%

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

Figueroa¹,

Martínez‐Oyanedel²,

Matamala³

et al. 2012

Protein Science

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“…Similar results (inter-hexamer rotation of 238 and interphycocyanin distance of 55.1 Å ) have recently been obtained for PC rods from Gracilaria chilensis by using a different docking algorithm. 46 …”

Section: Docking Model Of a Complex Of Two Phycocyaninsmentioning

confidence: 97%

A semiempirical approach to the intra‐phycocyanin and inter‐phycocyanin fluorescence resonance energy‐transfer pathways in phycobilisomes

et al. 2007

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A semiempirical methodology to model the intra-phycocyanin and inter-phycocyanin fluorescence resonance energy-transfer (FRET) pathways in the rods of the phycobilisomes (PBSs) from Fremyella diplosiphon is presented. Using the Förster formulation of FRET and combining experimental data and PM3 calculation of the dipole moments of the aromatic portions of the chromophores, transfer constants between pairs of chromophores in the phycocyanin (PC) structure were obtained. Protein docking of two PC hexamers was used to predict the optimal distance and axial rotation angle for the staked PCs in the PBSs' rods. Using the distance obtained by the docking process, transfer constants between pairs of chromophores belonging to different PC hexamers were calculated as a function of the angle of rotation. We show that six preferential FRET pathways within the PC hexameric ring and 15 pathways between hexamers exist, with transfer constants consistent with experimental results. Protein docking predicted the quaternary structure for PCs in rods with inter-phycocyanin distance of 55.6 A and rotation angle of 20.5 degrees . The inter-phycocyanin FRET constant between chromophores at positions beta(155) is maximized at the rotation angle predicted by docking revealing the crucial role of this specific inter-phycocyanin channel in defining the complete set of FRET pathways in the system.

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“…1) was an unexpected discovery, given the data from previously reported PBSs 3 . They do not make contact with the core and the energy they absorb would travel to the peripheral rods through a side-to-side interface 40 Fig. 11a).…”

Section: Plausible Energy Transfer Pathwaymentioning

confidence: 99%

Structure of phycobilisome from the red alga Griffithsia pacifica

Zhang

Liu

et al. 2017

Nature

204

199

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The cyanobacteria and red algae are two important groups of photosynthetic organisms that share a light-harvesting antenna known as the phycobilisome (PBS) [1][2][3][4] . PBSs are among the largest protein complexes in the living world and consist of phycobiliproteins (PBPs), including phycocyanin, phycoerythrin and allophycocyanin (APC), and linker proteins . Two subunits of PBPs, the α -and β -subunits, form an α β heterodimer that is conventionally called an (α β ) monomer. The monomer is then assembled into an (α β ) 3 trimer, the basic unit of PBS hierarchical assembly. The trimers of various PBPs are organized into a highly ordered supramolecular complex with the help of the linker proteins 1,5,6 . Four morphological types of PBS 1 are known: hemidiscoidal 7 , hemiellipsoidal 8 , block-type 9 and bundle-type 10. The hemidiscoidal PBS contains a central core surrounded by peripheral rods 1,11,12 . The chromophores in hemidiscoidal PBS are arranged in such a way that a photon absorbed by a chromophore in the peripheral rods is rapidly funnelled to chromophores in the core 13 and eventually to the terminal emitters (the core-membrane linker protein (L CM ) [14][15][16] or allophycocyanin D (ApcD) 17,18 ). The terminal emitters then transfer the energy to photosynthetic reaction centres 16,[19][20][21][22][23] . Currently, the mechanism of PBS assembly is poorly understood and the energy transfer routes within PBSs are not well defined. Although 3D structures of some individual PBPs have been reported (reviewed in refs 2, 3), the structures of most linker proteins are unknown and the complete structure of a PBS has not been published, to our knowledge. Here we report the cryo-electron microscopy (cryo-EM) structure of a PBS from the red alga Griffithsia pacifica at a resolution of 3.5 Å, which reveals details of the PBS architecture. Overall structureThe PBS from G. pacifica was purified and its intactness confirmed by its protein composition and spectroscopic features (Extended Data Fig. 1a-f). We reconstructed a 3D structure of the intact PBS by single particle cryo-EM with an overall resolution of 3.5 Å (Extended Data Table 1). Applying individual local masks improved the resolutions of local maps to 3.4-4.3 Å (Extended Data Fig. 2g). The PBS is one of the largest supramolecular complexes that has been reported, with a calculated molecular mass of approximately 16.8 megadaltons. The overall appearance is block-type 9 with twofold symmetry oriented perpendicularly to the thylakoid membranes (Fig. 1a-c and Extended Data Figs 1g-l, 3a-d). This PBS is larger than the hemiellipsoidal PBS isolated from Porphyridium cruentum8 and has dimensions of approximately 680 Å length, 390 Å height, and 450 Å thickness (Fig. 1a-c).The PBS contains a triangular core with the top cylinder B (formed by two APC trimers) sitting above two basal cylinders A and A′ (each formed by three APC trimers) surrounded by peripheral rods arranged in a staggered fashion (Fig. 1a-c and Extended Data Fig. 3c-e). In addition to the core and ...

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The structure at 2 Å resolution of Phycocyanin from Gracilaria chilensis and the energy transfer network in a PC–PC complex

Cited by 45 publications

References 44 publications

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

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

A semiempirical approach to the intra‐phycocyanin and inter‐phycocyanin fluorescence resonance energy‐transfer pathways in phycobilisomes

Structure of phycobilisome from the red alga Griffithsia pacifica

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