Crystal structure of Psb27 from Arabidopsis thaliana determined at a resolution of 1.85 Å

Cheng, Xingxing; Liu, Jiuyang; Zhang, Huan; Li, Fudong; Shuya, Zhang; Xu, Min; Ruan, Ke; Wang, Yuhua; Fu, Aigen

doi:10.1007/s11120-017-0450-3

Cited by 8 publications

(6 citation statements)

References 36 publications

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“…How Does Psb27 Facilitate Photoactivation? It has been shown that Psb27 is the vital player in PSII repair and assembly of the Mn 4 CaO 5 cluster of PSII that provides greater accessibility to the site of Mn-cluster assembly (32,33,36,(47)(48)(49). We find that Psb27 facilitates the photoactivation of the WOC in a more complex manner than simply displacing extrinsic polypeptides from apo-PSII.…”

Section: Discussionmentioning

confidence: 64%

The role of Ca ²⁺ and protein scaffolding in the formation of nature’s water oxidizing complex

Avramov

Hwang

Burnap

2020

Proc. Natl. Acad. Sci. U.S.A.

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Photosynthetic O2 evolution is catalyzed by the Mn4CaO5 cluster of the water oxidation complex of the photosystem II (PSII) complex. The photooxidative self-assembly of the Mn4CaO5 cluster, termed photoactivation, utilizes the same highly oxidizing species that drive the water oxidation in order to drive the incorporation of Mn2+ into the high-valence Mn4CaO5 cluster. This multistep process proceeds with low quantum efficiency, involves a molecular rearrangement between light-activated steps, and is prone to photoinactivation and misassembly. A sensitive polarographic technique was used to track the assembly process under flash illumination as a function of the constituent Mn2+ and Ca2+ ions in genetically engineered membranes of the cyanobacterium Synechocystis sp. PCC6803 to elucidate the action of Ca2+ and peripheral proteins. We show that the protein scaffolding organizing this process is allosterically modulated by the assembly protein Psb27, which together with Ca2+ stabilizes the intermediates of photoactivation, a feature especially evident at long intervals between photoactivating flashes. The results indicate three critical metal-binding sites: two Mn and one Ca, with occupation of the Ca site by Ca2+ critical for the suppression of photoinactivation. The long-observed competition between Mn2+ and Ca2+ occurs at the second Mn site, and its occupation by competing Ca2+ slows the rearrangement. The relatively low overall quantum efficiency of photoactivation is explained by the requirement of correct occupancy of these metal-binding sites coupled to a slow restructuring of the protein ligation environment, which are jointly necessary for the photooxidative trapping of the first stable assembly intermediate.

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Section: Discussionmentioning

confidence: 64%

The role of Ca ²⁺ and protein scaffolding in the formation of nature’s water oxidizing complex

Avramov

Hwang

Burnap

2020

Proc. Natl. Acad. Sci. U.S.A.

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“…It has been shown that Psb27 is the vital player in PSII repair and assembly of the Mn4CaO5 cluster of PSII that provides greater accessibility to the site of Mn-cluster assembly (31,32,35,(46)(47)(48). We find that Psb27 facilitates the photoactivation of the WOC in a more complex manner than simply displacing extrinsic polypeptides from apo-PSII.…”

Section: How Does Psb27 Facilitate Photoactivation?mentioning

confidence: 63%

The role of Ca²⁺and protein scaffolding in the formation in nature’s water oxidizing complex

Avramov

Hwang

Burnap

2020

Preprint

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The photosystem II (PSII) complex catalyzing the H2O-oxidation reaction of photosynthesis is highly prone to photodamage. Nature has evolved synthesis and repair mechanisms that include the photooxidative self-assembly, termed photoactivation, of the Mn4CaO5 metal cluster responsible for H2O-oxidation. Assembly is a multi-step light-driven process that proceeds with low quantum yield, involves a critical molecular rearrangement between light-activated steps, and is prone to photoinactivation and mis-assembly. A sensitive polarographic technique was used to track the assembly process under flash illumination as a function of the constituent Mn 2+ and Ca 2+ ions in genetically engineered samples to elucidate the action of Ca 2+ and peripheral proteins. We show that the protein scaffolding that organizes this process is modulated allosterically by the assembly protein Psb27, which together with Ca 2+ , stabilizes the intermediates of photoactivation, a feature especially evident at long intervals between photoactivating flashes. Besides stabilizing intermediates, the Ca 2+ ion is also critical to prevent photoinactivation due to inappropriate binding of Mn 2+ . Overexpression of Psb27, deletion of extrinsic protein PsbO, and excess Ca 2+ characteristically modify these processes and retard the dark rearrangement. The results suggest the involvement of three metal binding sites, two Mn and one Ca with occupation of the Ca site by Ca 2+ critical for the suppression of inactivation and the long-observed competition between Mn 2+ and Ca 2+ occurring at the second Mn site necessary for trapping the first stable assembly intermediates.. Significance StatementThe oxidation of water by the photosystem II is the foundation of bioproductivity on Earth and represents a blueprint for sustainable, carbon neutral technologies. Water oxidation is catalyzed by a metal cluster containing of 4 Mn and 1 Ca atoms linked via oxo bridges. The initial assembly is a complex sequential reaction harnessing the photochemical reaction center to photooxidatively incorporate Mn 2+ and Ca 2+ ions into the catalytic unit embedded in the protein matrix. This photoassembly is crucial for both de novo biosynthesis and as part of the 'self-healing' mechanism to cope with incessant photodamage that photosynthetic organisms experience. The results have implications for the natural mechanism as well as the highly desirable biomimetic devices currently envisioned for solar energy production.

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“…These inactive Psb27-PSII complexes are deficient in the Mn 4 CaO 5 cluster and three extrinsic subunits: PsbO, PsbV, and PsbU. The structure of Psb27 has been solved by both solution NMR (41,42) and X-ray crystallography (43,44), and its association with PSII assembly intermediate has been studied by chemical cross-linking analysis and mass spectrometry (45)(46)(47)(48). These studies suggested that Psb27 binds to the large extrinsic E-loop of CP43 at the luminal side; however, there are discrepancies regarding the detailed binding sites of Psb27 in PSII (45)(46)(47)(48).…”

Section: Significancementioning

confidence: 99%

Structural insights into a dimeric Psb27-photosystem II complex from a cyanobacterium Thermosynechococcus vulcanus

Huang

Xiao

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Photosystem II (PSII) is a multisubunit pigment-protein complex and catalyzes light-driven water oxidation, leading to the conversion of light energy into chemical energy and the release of molecular oxygen. Psb27 is a small thylakoid lumen-localized protein known to serve as an assembly factor for the biogenesis and repair of the PSII complex. The exact location and binding fashion of Psb27 in the intermediate PSII remain elusive. Here, we report the structure of a dimeric Psb27-PSII complex purified from a psbV deletion mutant (ΔPsbV) of the cyanobacterium Thermosynechococcus vulcanus, solved by cryo-electron microscopy. Our structure showed that Psb27 is associated with CP43 at the luminal side, with specific interactions formed between Helix 2 and Helix 3 of Psb27 and a loop region between Helix 3 and Helix 4 of CP43 (loop C) as well as the large, lumen-exposed and hydrophilic E-loop of CP43. The binding of Psb27 imposes some conflicts with the N-terminal region of PsbO and also induces some conformational changes in CP43, CP47, and D2. This makes PsbO unable to bind in the Psb27-PSII. Conformational changes also occurred in D1, PsbE, PsbF, and PsbZ; this, together with the conformational changes occurred in CP43, CP47, and D2, may prevent the binding of PsbU and induce dissociation of PsbJ. This structural information provides important insights into the regulation mechanism of Psb27 in the biogenesis and repair of PSII.

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Crystal structure of Psb27 from Arabidopsis thaliana determined at a resolution of 1.85 Å

Cited by 8 publications

References 36 publications

The role of Ca ²⁺ and protein scaffolding in the formation of nature’s water oxidizing complex

The role of Ca ²⁺ and protein scaffolding in the formation of nature’s water oxidizing complex

The role of Ca²⁺and protein scaffolding in the formation in nature’s water oxidizing complex

Structural insights into a dimeric Psb27-photosystem II complex from a cyanobacterium Thermosynechococcus vulcanus

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Crystal structure of Psb27 from Arabidopsis thaliana determined at a resolution of 1.85 Å

Cited by 8 publications

References 36 publications

The role of Ca 2+ and protein scaffolding in the formation of nature’s water oxidizing complex

The role of Ca 2+ and protein scaffolding in the formation of nature’s water oxidizing complex

The role of Ca2+and protein scaffolding in the formation in nature’s water oxidizing complex

Structural insights into a dimeric Psb27-photosystem II complex from a cyanobacterium Thermosynechococcus vulcanus

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The role of Ca ²⁺ and protein scaffolding in the formation of nature’s water oxidizing complex

The role of Ca ²⁺ and protein scaffolding in the formation of nature’s water oxidizing complex

The role of Ca²⁺and protein scaffolding in the formation in nature’s water oxidizing complex