Chlorophyll <i>a/b</i> proteins of Photosystem I

Lam, Eric; Ortiz, William; Malkin, Richard

doi:10.1016/0014-5793(84)80197-0

Cited by 168 publications

(96 citation statements)

References 9 publications

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“…However, several points of interest in this model are relevant to our current knowledge on the structure-function relationship in the PSI complex. The (15,20,21,30) and these polypeptides have different organizational characteristics with the 23 kD peptide being the most stromal exposed and the 22 kD peptide less exposed. The 20 kD polypeptide is inaccessible to the probes we have used and this polypeptide would appear to be totally buried in the thylakoid membrane.…”

Section: Topography Of Psi In Thylakoidsmentioning

confidence: 99%

“…The antibodies to the 20 kD polypeptide (Fig. 9A), also known as LHCPIb (20), demonstrate that no significant digestion of this peptide occurred, even at the highest pronase concentration used. The antibody against the apoprotein ofCPI (62 kD), on the other hand, cross-reacted with the 48, 30 (Fig.…”

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confidence: 94%

“…6), according to (13,20). An aliquot of the antenna-depleted PSI complex was also relabeled with approach taken has been to examine the modification of plastocyanin, a mobile electron carrier that is located in the lumenal space (14).…”

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Topography of the Protein Complexes of the Chloroplast Thylakoid Membrane

Ortiz¹,

Lam²,

Chollar³

et al. 1985

Plant Physiol.

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The transverse heterogeneity of the polypeptides associated with the Photosystem I (PSI) complex in spinach thylakoid membranes and in a highly resolved PSI preparation has been studied using the impermeant chemical modifier, 2,4,6-trinitrobenzenesulfonate (TNBS) and the proteolytic enzyme, Pronase E. The present study has shown that the PSI reaction center polypeptide of -62 kilodaltons and the 22 and 20 kilodalton polypeptides of the PSI light-harvesting chlorophyll protein (LHCPI) complex are not labeled by I'4CFTNBS in unfractionated thylakoids. On the other hand, the 23 kilodalton polypeptide of the PSI LHCP and the 19 and 14 kilodalton polypeptides associated with the PSI primary electron acceptor complex are readily labeled by I"4CITNBS and are exposed to the stromal side of the thylakoid. Differences and similarities in the labeling of polypeptides associated with the PSI complex in thylakoids and in the isolated PSI complex are also noted. Treatment of thylakoids with pronase had no effect on the organization of the polypeptides in the LHCPI or the reaction center core complex, as manifested by the separation of these two subcomplexes from pronasetreated membranes. The 62, 19, and 14 kilodalton polypeptides associated with the reaction center core complex and the 23 and 22 kilodalton polypeptides associated with LHCPI are sensitive to pronase treatment while the 20 kilodalton polypeptide of LHCPI was inaccessible to the protease. The proteolysis of the 62 kilodalton polypeptide generated first a single immunodetectable fragment at about 48 kilodaltons, and further proteolytic digestion generated two other fragments at 30 and 17 kilodaltons respectively. These results are discussed in relation to the organization of the PSI complex in spinach thylakoids. A model for the transmembrane topography of the polypeptide constituents of PSI has been developed. complexes to the overall structure of the chloroplast membrane is less well understood.It has recently been possible to isolate all the chloroplast membrane electron transfer complexes in highly resolved functional form (7,16,25), and subsequently it has been demonstrated that these complexes are reconstitutively active in catalyzing noncyclic electron transport from water to NADP when supplemented with soluble protein cofactors (19). The availability of these resolved complexes allows for detailed examination of structure-function relationships in the individual complexes and examination of the nature of the interactions between complexes. In the present study, we have considered the topographical orientation of the chloroplast PSI complex. The impermeant chemical probe, TNBS,3 labeled with "1C, has been used to modify stroma-exposed amino acid side chains on proteins in unfractionated thylakoid membranes and reactive groups in the resolved PSI complex of Mullet et al. (25). The labeling pattern of PSI polypeptides in the membranes has been compared with that of the isolated PSI complex and subfractions isolated from this complex. Since any one sp...

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Section: Topography Of Psi In Thylakoidsmentioning

confidence: 99%

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confidence: 94%

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Topography of the Protein Complexes of the Chloroplast Thylakoid Membrane

Ortiz¹,

Lam²,

Chollar³

et al. 1985

Plant Physiol.

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“…LHCI can be subfractionated into two populations called LHCI-680 and LHCI-730 according to their 77 K (Kelvin) fluorescence emission maximum (24). The former is composed of polypeptides with 23 and 24 kDa (Lhca2 and Lhca3, respectively), and the latter is composed of polypeptides with 21 and 20.5 kDa (Lhca1 and Lhca4, respectively) (25)(26)(27). Use of other detergent mixtures for PS I solubilization in combination with improved separation techniques allowed splitting of LHCI-680 into two different fractions, one enriched in Lhca2 (LHCI-680B) and the other enriched in Lhca3 (LHCI-680A) (26,27).…”

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Pigment Binding of Photosystem I Light-harvesting Proteins

Schmid

Potthast

Wiener

et al. 2002

Journal of Biological Chemistry

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“…However, in vitro reconstitution has demonstrated a heterodimerization of Lhca5 with Lhca1 [15] and Lhca5 was found together with Lhca1 and Lhca4 in dimeric fractions of LHCI-730 [14] implicating the possibility for Lhca1/a5 heterodimers or Lhca5 homodimers in vivo. But as Da4 plants which show highest amounts of Lhca5 do not even accumulate Lhca1 on a thylakoid level [9] the presence of Lhca5/a1 heterodimers in Arabidopsis in vivo is unlikely. Obviously, interaction of Lhca proteins with PSI core proteins plays a major role in determining the interaction properties of some Lhca proteins.…”

Section: Resultsmentioning

confidence: 99%

Lhca5 interaction with plant photosystem I

Luciński¹,

Schmid²,

Jansson³

et al. 2006

FEBS Letters

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In the outer antenna (LHCI) of higher plant photosystem I (PSI) four abundantly expressed light-harvesting protein of photosystem I (Lhca)-type proteins are organized in two heterodimeric domains (Lhca1/Lhca4 and Lhca2/Lhca3). Our cross-linking studies on PSI-LHCI preparations from wildtype Arabidopsis and pea plants indicate an exclusive interaction of the rarely expressed Lhca5 light-harvesting protein with LHCI in the Lhca2/Lhca3-site. In PSI particles with an altered LHCI composition Lhca5 assembles in the Lhca1/Lhca4 site, partly as a homodimer. This flexibility indicates a binding-competitive model for the LHCI assembly in plants regulated by molecular interactions of the Lhca proteins with the PSI core.

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Chlorophyll a/b proteins of Photosystem I

Cited by 168 publications

References 9 publications

Topography of the Protein Complexes of the Chloroplast Thylakoid Membrane

Topography of the Protein Complexes of the Chloroplast Thylakoid Membrane

Pigment Binding of Photosystem I Light-harvesting Proteins

Lhca5 interaction with plant photosystem I

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