Topography of the Photosystem I Core Proteins of the Cyanobacterium Synechocystis sp. PCC 6803

Sun, Jun; Xu, Qiang; Chitnis, Vaishali P.; Park, Jin; Chitnis, Parag R.

doi:10.1074/jbc.272.35.21793

Cited by 26 publications

(20 citation statements)

References 47 publications

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“…An assignment of primed or unprimed ␣-helices to PsaA or PsaB is still not possible on purely structural grounds (however, see Ref. 46). …”

Section: Resultsmentioning

confidence: 99%

“…Recently, protease cleavage site analysis of PsaA and PsaB proposed mapping the subunit PsaA to the primed core ␣-helices and PsaB to the nonprimed (46). This assignment is based on the finding that the absence of PsaE opens additional protease cleavage sites on PsaA, while the absence of PsaD leads to new cleavage products in the N-terminal region of PsaB.…”

Section: Orientation Of Psae In the Psimentioning

confidence: 99%

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Photosystem I, an Improved Model of the Stromal Subunits PsaC, PsaD, and PsaE

Klukas¹,

Schubert²,

Jordan³

et al. 1999

Journal of Biological Chemistry

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The spatial orientation with respect to other subunits is described as well as the possible interactions between the stromal subunits. A first model of PsaD consisting of a four-stranded ␤-sheet and an ␣-helix is suggested, indicating that this subunit partly shields PsaC from the stromal side. In addition to the improvements on the stromal subunits, the structural model of the membrane-integral region of PSI is also extended. The current electron density map allows the identification of the N and C termini of the subunits PsaA and PsaB. The 11-transmembrane ␣-helices of these subunits can now be assigned uniquely to the hydrophobic segments identified by hydrophobicity analyses.

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“…An assignment of primed or unprimed ␣-helices to PsaA or PsaB is still not possible on purely structural grounds (however, see Ref. 46). …”

Section: Resultsmentioning

confidence: 99%

Section: Orientation Of Psae In the Psimentioning

confidence: 99%

Photosystem I, an Improved Model of the Stromal Subunits PsaC, PsaD, and PsaE

Klukas¹,

Schubert²,

Jordan³

et al. 1999

Journal of Biological Chemistry

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show abstract

“…3B). This may be due to differential proteolysis in the two organisms and possibly influenced by the levels of the other smaller PSI polypeptides around the core complex as demonstrated in other organisms (Sun et al, 1997). PsaA/B in E. chlorotica never declined below 45% to 50% of month 1 levels or algal levels.…”

Section: Immunoblot Analysis Of Chloroplast Proteinsmentioning

confidence: 99%

“…Polyclonal, heterologous antibodies directed against D1, D2, and CP43 (all from barley), FCP (diatom), PsaA and PsaB (domain specific Synechocystis sp. PCC 6803 synthetic peptides [Sun et al, 1997]), PsaC and PsaD (Synechocystis sp. PCC 6803), and cyt f (Chlamydomonas reinhardtii), were raised in rabbits and generously provided to us by a number of sources (please see "Acknowledgments").…”

Section: Immunoblot Analysis and Quantificationmentioning

confidence: 99%

Mollusc-Algal Chloroplast Endosymbiosis. Photosynthesis, Thylakoid Protein Maintenance, and Chloroplast Gene Expression Continue for Many Months in the Absence of the Algal Nucleus

et al. 2000

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Early in its life cycle, the marine mollusc Elysia chlorotica Gould forms an intracellular endosymbiotic association with chloroplasts of the chromophytic alga Vaucheria litorea C. Agardh. As a result, the dark green sea slug can be sustained in culture solely by photoautotrophic CO 2 fixation for at least 9 months if provided with only light and a source of CO 2 . Here we demonstrate that the sea slug symbiont chloroplasts maintain photosynthetic oxygen evolution and electron transport activity through photosystems I and II for several months in the absence of any external algal food supply. This activity is correlated to the maintenance of functional levels of chloroplast-encoded photosystem proteins, due in part at least to de novo protein synthesis of chloroplast proteins in the sea slug. Levels of at least one putative algal nuclear encoded protein, a light-harvesting complex protein homolog, were also maintained throughout the 9-month culture period. The chloroplast genome of V. litorea was found to be 119.1 kb, similar to that of other chromophytic algae. Southern analysis and polymerase chain reaction did not detect an algal nuclear genome in the slug, in agreement with earlier microscopic observations. Therefore, the maintenance of photosynthetic activity in the captured chloroplasts is regulated solely by the algal chloroplast and animal nuclear genomes.

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“…Isolation of Thylakoid Membranes and PS I Complexes-Thylakoid membranes were prepared from cells as described previously (18). The membranes were pelleted by centrifugation at 50,000 ϫ g for 90 min and resuspended in SMN (0.4 M sucrose, 10 mM MOPS at pH 7.0, 10 mM NaCl) buffer.…”

Section: Cyanobacterial Strains and Growth-a Glucose-tolerant Strain Ofmentioning

confidence: 99%

Recruitment of a Foreign Quinone into the A1 Site of Photosystem I

Johnson

Zybailov

Jones

et al. 2001

Journal of Biological Chemistry

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Substituted quinones are usually employed as cofactors in electron transport chains, as demonstrated in bacterial reaction centers (1, 2), and in the two photosystems of plants and cyanobacteria (3-5). These quinones comprise a relatively polar ring, which consists of either a benzoquinone (BQ) 1 or a naphthoquinone (NQ) "head group" and a non-polar isoprenoid "tail" of various chain lengths and degrees of saturation. Benzoquinones such as plastoquinone-9 (PQ-9) and ubiquinone-10 function either as fixed or exchangeable electron/proton carriers during photosynthetic and respiratory electron transport. In photosystem II (PS II), PQ-9 functions as a bound one-electron cofactor in the Q A site and as an exchangeable two-electron/ two-proton cofactor in the Q B site. The reduced PQH 2 -9 is displaced from the Q B site, diffuses laterally through the membrane, and becomes oxidized and deprotonated by the cytochrome b 6 f complex. Photosynthetic reaction centers (RCs) of purple bacteria use either ubiquinone-10 (e.g. Rhodobacter sphaeroides) in a similar double role or menaquinone-9 in the Q A site (e.g. Rhodosprillulum viridis). In photosystem I (PS I), phylloquinone (PhQ), a substituted 1,4-NQ with a 20-carbon, largely saturated phytyl tail, functions as a bound one-electron cofactor in the A 1 site. PS I contains two PhQ molecules/P700, but neither of the two quinones functions in a manner equivalent to Q B in the bacterial RC and PS II. Instead, the electron is transferred from the active quinone(s) to soluble ferredoxin via a chain of three bound iron-sulfur centers. Quinones are therefore extremely versatile; they can function as the interface between electron transfer involving organic cofactors and electron transfer involving iron-sulfur clusters (as in PS I), or between pure electron transfer and coupled electron/proton transfer involving a second organic cofactor (as in PS II). Each quinone displays equilibrium binding and redox properties that can be very different for each site of interaction (6), and these properties are conferred largely by the protein environment.To understand the structural determinants that allow quinones to function with a low redox potential in the A 1 site of PS I, we embarked on a project aimed at biological replacement of

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Topography of the Photosystem I Core Proteins of the Cyanobacterium Synechocystis sp. PCC 6803

Cited by 26 publications

References 47 publications

Photosystem I, an Improved Model of the Stromal Subunits PsaC, PsaD, and PsaE

Photosystem I, an Improved Model of the Stromal Subunits PsaC, PsaD, and PsaE

Mollusc-Algal Chloroplast Endosymbiosis. Photosynthesis, Thylakoid Protein Maintenance, and Chloroplast Gene Expression Continue for Many Months in the Absence of the Algal Nucleus

Recruitment of a Foreign Quinone into the A1 Site of Photosystem I

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