Identification of the plastocyanin binding subunit of photosystem I

Hippler, Michael; Ratajczak, Rafael; Haehnel, Wolfgang

doi:10.1016/0014-5793(89)80738-0

Cited by 111 publications

(56 citation statements)

References 21 publications

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“…35 the proteins were electroblotted onto nitrocellulose and incubated with antibodies as described (36). Immuno-detection was carried out according to Ref.…”

Section: Sds-page and Westernmentioning

confidence: 99%

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Limitation in Electron Transfer in Photosystem I Donor Side Mutants of Chlamydomonas reinhardtii

Hippler¹,

Biehler²,

Krieger‐Liszkay³

et al. 2000

Journal of Biological Chemistry

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Strains of Chlamydomonas reinhardtii lacking thePsaF gene or containing the mutation K23Q within the N-terminal part of PsaF are sensitive to high light (>400 E m ؊2 s ؊1 ) under aerobic conditions. In vitro experiments indicate that the sensitivity to high light of the isolated photosystem I (PSI) complex from wild type and from PsaF mutants is similar. In vivo measurements of photochemical quenching and oxygen evolution show that impairment of the donor side of PSI in the PsaF mutants leads to a diminished linear electron transfer and/or a decrease of photosystem II (PSII) activity in high light. Thermoluminescence measurements indicate that the PSII reaction center is directly affected under photo-oxidative stress when the rate of electron transfer becomes limiting in the PsaF-deficient strain and in the PsaF mutant K23Q. We have isolated a high light-resistant PsaF-deficient suppressor strain that has a high chlorophyll a/b ratio and is affected in the assembly of light-harvesting complex. These results indicate that under high light a functionally intact donor side of PSI is essential for protection of C. reinhardtii against photo-oxidative damage when the photosystems are properly connected to their light-harvesting antennae.Photosynthesis is driven by light. Photons are absorbed by pigments of the light harvesting chlorophyll-carotenoid-protein complexes that are associated with the membrane embedded photosynthetic reaction centers. Excitation energy can be transferred to the reaction centers where it induces charge separation across the membrane. This leads to a series of electron transfer reactions resulting in oxidation of water and the production of chemical energy in the form of ATP and NADPH, which are used for CO 2 fixation. If the absorption of light exceeds the capacity of photosynthetic energy consumption, over-reduction of the electron transport carriers and increase of the lifetime of excited states in the light-harvestingantennae occur. Over-reduction of the electron carriers can lead to photo-oxidative damage by reactive oxygen species. O 2 can be directly reduced by PSI 1 (1) generating superoxide anion radical (O 2 . ) and other reactive oxygen species. Increase in the lifetime of excited singlet chlorophyll increases the probability of triplet chlorophyll formation, which can react with O 2 to produce 1 O 2 (2, 3). Reactive oxygen species cause photo-oxidative damage, especially to PSII, which is considered to be the primary target for photoinhibition (4 -6). Thus, mechanisms that balance energy input through photochemistry with energy consumption through CO 2 assimilation and other metabolic pathways are essential for plant survival.Mechanisms that balance energy input and consumption can be divided into short and long term responses. Short term responses include nonphotochemical dissipation of excess energy (7, 8) and reduction of energy transfer to PSII through state transition, a process that leads to a redistribution of excitation energy to PSI by a reorganization of the antennae (...

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“…35 the proteins were electroblotted onto nitrocellulose and incubated with antibodies as described (36). Immuno-detection was carried out according to Ref.…”

Section: Sds-page and Westernmentioning

confidence: 99%

“…22. For N-terminal amino acid sequencing proteins were blotted onto polyvinylidene difluoride membranes (36).…”

Section: Sds-page and Westernmentioning

confidence: 99%

Limitation in Electron Transfer in Photosystem I Donor Side Mutants of Chlamydomonas reinhardtii

Hippler¹,

Biehler²,

Krieger‐Liszkay³

et al. 2000

Journal of Biological Chemistry

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“…The structural and phylogenetic relationship between the cyt bc 1 and the cyt bf complex suggests that a similar mechanism operates in both membrane assemblies. In plants, most algae and some cyanobacteria it is plastocyanin which accepts electrons from cyt f and transfers them to P700, the reaction center chlorophyll of photosystem I (PSI) (7)(8)(9). While the interaction of plastocyanin with PSI has been studied extensively by different groups with consistent results (8, 10 -14), that with the cyt bf complex is considerably less understood and controversial.…”

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“…One is the flat hydrophobic area around the solventexposed copper ligand His-87, and the other is composed of two conserved acidic patches, Asp-42/Glu-43/Asp-44/Glu-45 and Glu-59/Glu-60/Asp-61, both adjacent to Tyr-83. To investigate the role of these elements in the interaction with PSI, crosslinking between plastocyanin and PSI (8,9,16), as well as measurements of electron transfer kinetics with site-directed plastocyanin mutants (9,10,12,14), have been conducted. The results suggest that in the complex the electron transfer occurs via the copper ligand His-87 (10,12) and that, apart from the interaction of the hydrophobic area, only the negative patch of residues 42-45 contributes substantially an electrostatic attraction to a positive domain of the PsaF subunit of PSI in plants (9,13,14).…”

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Dynamic Interaction of Plastocyanin with the Cytochrome bf Complex

Illerhaus

Altschmied

Reichert

et al. 2000

Journal of Biological Chemistry

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The interaction between plastocyanin and the intact cytochrome bf complex, both from spinach, has been studied by stopped-flow kinetics with mutant plastocyanin to elucidate the site of electron transfer and the docking regions of the molecule. Mutation of Tyr-83 to Arg or Leu provides no evidence for a second electron transfer path via Tyr-83 of plastocyanin, which has been proposed to be the site of electron transfer from cytochrome f. The data found with mutations of acidic residues indicate that both conserved negative patches are essential for the binding of plastocyanin to the intact cytochrome bf complex. Replacing Ala-90 and Gly-10 at the flat hydrophobic surface of plastocyanin by larger residues slowed down and accelerated, respectively, the rate of electron transfer as compared with wild-type plastocyanin. These opposing effects reveal that the hydrophobic region around the electron transfer site at His-87 is divided up into two regions, of which only that with Ala-90 contributes to the attachment to the cytochrome bf complex. These binding sites of plastocyanin are substantially different from those interacting with photosystem I. It appears that each of the two binding regions of plastocyanin is split into halves, which are used in different combinations in the molecular recognition at the two membrane complexes.

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“…There have been several attempts to describe the interactions between plastocyanin and its biological redox partners [5,6]. Other experiments have been based on chemical modifications of amino acid residues [7,8] and binding of inorganic complexes [9] to the presumed bin- Abbreviations: IPTG, isopropyl-b-D-thiogalactopyranoside; RBS, ribosome binding site; SDS-PAGE, sodium dodecyl sulphate-polyacrylamide gel electrophoresis; EPR, electronic paramagnetic resonance; CD, circular dichroism ding sites.…”

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Expression of spinach plastocyanin in E. coli

1990

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An expression vector designed for overexpression of plastocyanin in the periplasmic space of E. coli has been developed. The vector contains the signal peptide sequence of Pseudomonas ueruginosu azurin and the mature sequence of spinach plastocyanin. The precursor is efficiently translocated to the periplasmic space and correctly processed to mature plastocyanin. No detectable amount of plastocyanin was present in the cytoplasmic or in the membrane fraction. A large scale preparation of the recombinant plastocyanin in a 20 litre fermentor yielded approximately 30 mg of pure plastocyanin. The recombinant protein obtained from E. coli shows CD, EPR and optical properties identical to plastocyanin isolated from spinach.

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Identification of the plastocyanin binding subunit of photosystem I

Cited by 111 publications

References 21 publications

Limitation in Electron Transfer in Photosystem I Donor Side Mutants of Chlamydomonas reinhardtii

Limitation in Electron Transfer in Photosystem I Donor Side Mutants of Chlamydomonas reinhardtii

Dynamic Interaction of Plastocyanin with the Cytochrome bf Complex

Expression of spinach plastocyanin in E. coli

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