scholarly journals Evidence for two-step processing of nuclear-encoded chloroplast proteins during membrane assembly.

1986 ◽  
Vol 103 (3) ◽  
pp. 725-731 ◽  
Author(s):  
C P Chia ◽  
C J Arntzen
Keyword(s):  
Water Oxidation ◽  
Size Class ◽  
Proteolytic Processing ◽  
Chloroplast Envelope ◽  
Second Step ◽  
Core Complex ◽  
Intermediate Size ◽  
Polymorphic Forms ◽  
Inside Out ◽  
Psii Core Complex

A plastome (chloroplast genome) mutant of tobacco, lutescens-1, displays abnormal degradation of the chloroplast-encoded polypeptides which form the core complex of photosystem II (PSII). Two nuclear-encoded proteins (present in polymorphic forms), which normally function in the water oxidation process of PSII, accumulate as larger size-class polypeptides in mutant thylakoid membranes. These accumulated proteins are intermediate in size between the full-length primary protein synthesized in the cytoplasm and the proteolytically processed mature polypeptides. Trypsin treatment of unstacked mutant thylakoids and of inside-out vesicle (PSII-enriched) preparations indicated that the intermediate size forms were correctly localized on the inner surface of the thylakoid membrane, but not surface-exposed in the same way as the mature proteins. Only one of the intermediate size-class proteins could be extracted by salt washes. We interpret these data to be consistent with the idea that the two imported proteins that function in the water oxidation step of photosynthesis and are localized in the loculus (the space within the thylakoid vesicles) undergo two-step processing. The second step in proteolytic processing may be related to transport through a second membrane (the first transport step through the chloroplast envelope having been completed); this step may be arrested in the mutant due to the absence of the PSII core complex.

Effect of MgCl2 and Phosphatidylglycerol on CaCl2-Mediated Recovery of Oxygen Evolution in a Photosystem II Complex Depleted of the 17 and 24 kDa Extrinsic Proteins

1998 ◽  
Vol 53 (1-2) ◽  
pp. 39-48 ◽  
Author(s):  
E. K. Nénonéné ◽  
M. Méthot ◽  
M. Fragata
Keyword(s):  
Oxygen Evolution ◽  
Water Oxidation ◽  
Higher Plants ◽  
Molecular System ◽  
Chloride Ions ◽  
Core Complex ◽  
Higher Plant ◽  
Oscillatoria Chalybea ◽  
Extrinsic Proteins ◽  
Psii Core Complex

Abstract Phosphatidylglycerol (PG) is an anionic lipid of the thylakoid membrane of higher plant chloroplasts. PG was shown previously to stimulate the evolution of oxygen in intact pho­tosystem II (PSII) membranes [Fragata, M., Strzałka, K. and Nénonéné, E. K. (1991) J. Photochem. Photobiol. B: Biol 11, 329-342], In this work, a study was undertaken of the effect of MgCl2 and PG on the CaCl2-mediated recovery of oxygen evolution in a PSII complex depleted of the extrinsic proteins (EP) of molecular masses 17 kDa (EP17) and 24 kDa (EP24), hereunder designated d17.24PSII. This molecular system is structurally close to the PSII core complex of cyanobacteria and is therefore useful in the comparative analysis of PSII-PG relationships in cyanobacteria and the higher plants. This work reveals a new aspect of the thylakoid lipids role in the PSII function, namely the PG effect on intact PSII is observed as well in d17.24PSII. The results show that phosphatidylglycerol has the ability to compensate for the loss of EP17 and EP24 in the PSII complex. That is, PG restores the oxygen evolution in d17.24PSII incubated in the presence of MgCl2 and/or CaCl2 to the levels observed in native PSII. Moreover, the site of H2O degradation in d17.24PSII, including most probably the pool of calcium and chloride ions, would seem to be protected by phosphatidyl­glycerol. This suggests that one of the docking sites of PG in the PSII complex is near EP24, inasmuch as this extrinsic protein participates in the regulation of the affinity of the calcium and chloride ions to the water oxidation site. Furthermore, taking into account that in d17.24PSII the PSII core complex is directly exposed to PG, then the phospholipid effect reported here indicates that phosphatidylglycerol might be a functional effector and mem­brane anchor of the D1 protein in the PSII core complex as was shown recently in the cyanobacterium Oscillatoria chalybea [Kruse, O. and Schmid, G. H. (1995) Z. Naturforsch. 50c, 380-390],

Comparative ultrastructure of eyespot membranes in gametes and zoospores of the green alga Ulva lactuca (Ulvales)

1981 ◽  
Vol 50 (1) ◽  
pp. 149-164
Author(s):  
H. Robenek ◽  
M. Melkonian
Keyword(s):  
Green Alga ◽  
Freeze Fracture ◽  
Size Class ◽  
Ulva Lactuca ◽  
Chloroplast Envelope ◽  
Envelope Membrane ◽  
Chloroplast Membrane ◽  
Green Algal ◽  
Male Gametes ◽  
Chloroplast Envelope Membrane

Eyespot membranes in zoospores, and male and female gametes of the green alga Ulva lactuca, were studied comparatively by the freeze-fracture technique. The plasmalemma and the outer chloroplast envelope membrane overlying the eyespot lipid globules are specialized in all 3 types of reproductive cells. In the eyespot region the protoplasmic face (PF) of the outer chloroplast envelope membrane contains significantly more intramembraneous particles (IMP) compared to membrane areas outside the eyespot: in female gametes there are 2.5 times more IMP/micrometers 2, in zoospores 3 and in male gametes about 4. Small size-class IMP (4–6 nm diameter) are particularly abundant on both fracture faces of the outer chloroplast membrane, but size-class distribution is not significantly different between membrane areas inside and outside the eyespot region. The total number of IMP/eyespot on the PF of the outer chloroplast membrane was calculated to be 4900 in male gametes, 5500 in female gametes and 11 200 in zoospores. The results are discussed in accordance with the view that these membrane specializations participate in photoreception relating to green algal phototaxis. Evidence is presented that there is a correlation between IMP numbers per eyespot in the outer chloroplast envelope membrane and the different phototactic behaviour of gametes compared to zoospores in Ulva.

Relationships between heterogeneity of the PSII core complex from grana particles and phosphorylation

1991 ◽  
Vol 176 (3) ◽  
pp. 1298-1305 ◽  
Author(s):  
Maria T. Giardi ◽  
Fernanda Rigoni ◽  
Roberto Barbato ◽  
Giorgio M. Giacometti
Keyword(s):  
Core Complex ◽  
Psii Core Complex

L Protein Supported Quinone Exchange at QA Site in PSII Core Complex

1995 ◽  
pp. 535-538
Author(s):  
Shinichiro Ozawa ◽  
Hisashi Hoshida ◽  
Yoshinori Toyoshima
Keyword(s):  
Core Complex ◽  
L Protein ◽  
Psii Core Complex

scholarly journals Reconstitution of protein targeting to the inner envelope membrane of chloroplasts

2006 ◽  
Vol 175 (2) ◽  
pp. 249-259 ◽  
Author(s):  
Ming Li ◽  
Danny J. Schnell
Keyword(s):  
Lipid Metabolism ◽  
Protein Targeting ◽  
Chloroplast Envelope ◽  
Envelope Membrane ◽  
Stromal Compartment ◽  
Intermediate Size ◽  
Envelope Membranes ◽  
Inner Envelope

The chloroplast envelope plays critical roles in the synthesis and regulated transport of key metabolites, including intermediates in photosynthesis and lipid metabolism. Despite this importance, the biogenesis of the envelope membranes has not been investigated in detail. To identify the determinants of protein targeting to the inner envelope membrane (IM), we investigated the targeting of the nucleus-encoded integral IM protein, atTic40. We found that pre-atTic40 is imported into chloroplasts and processed to an intermediate size (int-atTic40) before insertion into the IM. Int-atTic40 is soluble and inserts into the IM from the internal stromal compartment. We also show that atTic40 and a second IM protein, atTic110, can target and insert into isolated IM vesicles in vitro. Collectively, our experiments are consistent with a “postimport” mechanism in which the IM proteins are first imported from the cytoplasm and subsequently inserted into the IM from the stroma.

Effects of mild trypsinization on the properties of a (17, 23 and 33 kDa)-retaining PSII core complex

1995 ◽  
pp. 1283-1286
Author(s):  
E. Kouimtzoglou ◽  
R. K. Mishra ◽  
M. Haumann ◽  
W. Junge ◽  
D. F. Ghanotakis
Keyword(s):  
Core Complex ◽  
Psii Core Complex

scholarly journals Cyanobacterial Small Chlorophyll-binding Protein ScpD (HliB) Is Located on the Periphery of Photosystem II in the Vicinity of PsbH and CP47 Subunits

2006 ◽  
Vol 281 (43) ◽  
pp. 32705-32713 ◽  
Author(s):  
Kamoltip Promnares ◽  
Josef Komenda ◽  
Ladislav Bumba ◽  
Jana Nebesarova ◽  
Frantisek Vacha ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Binding Proteins ◽  
Particle Image ◽  
Sequence Similarity ◽  
Core Complex ◽  
Significant Sequence Similarity ◽  
Large Structures ◽  
A Cell ◽  
Sds Electrophoresis ◽  
Psii Core Complex

Cyanobacteria contain several genes coding for small one-helix proteins called SCPs or HLIPs with significant sequence similarity to chlorophyll a/b-binding proteins. To localize one of these proteins, ScpD, in the cells of the cyanobacterium Synechocystis sp. PCC 6803, we constructed several mutants in which ScpD was expressed as a His-tagged protein (ScpDHis). Using two-dimensional native-SDS electrophoresis of thylakoid membranes or isolated Photosystem II (PSII), we determined that after high-light treatment most of the ScpDHis protein in a cell is associated with PSII. The ScpDHis protein was present in both monomeric and dimeric PSII core complexes and also in the core subcomplex lacking CP43. However, the association with PSII was abolished in the mutant lacking the PSII subunit PsbH. In a PSII mutant lacking cytochrome b559, which does not accumulate PSII, ScpDHis is associated with CP47. The interaction of ScpDHis with PsbH and CP47 was further confirmed by electron microscopy of PSII labeled with Ni-NTA Nanogold. Single particle image analysis identified the location of the labeled ScpDHis at the periphery of the PSII core complex in the vicinity of the PsbH and CP47. Because of the fact that ScpDHis did not form any large structures bound to PSII and because of its accumulation in PSII subcomplexes containing CP47 and PsbH we suggest that ScpD is involved in a process of PSII assembly/repair during the turnover of pigment-binding proteins, particularly CP47.

A theoretical study on the dynamics of light harvesting in the dimeric photosystem II core complex: regulation and robustness of energy transfer pathways

2019 ◽  
Vol 216 ◽  
pp. 94-115 ◽  
Author(s):  
Shou-Ting Hsieh ◽  
Lu Zhang ◽  
De-Wei Ye ◽  
Xuhui Huang ◽  
Yuan-Chung Cheng
Keyword(s):  
Energy Transfer ◽  
Photosystem Ii ◽  
Theoretical Study ◽  
Light Harvesting ◽  
Coarse Grained ◽  
Core Complex ◽  
Coarse Grained Model ◽  
Complex Regulation ◽  
Psii Core Complex

Coarse-grained model for dimeric PSII core complex reveals robust light harvesting through inter-monomer energy transfer and pooling in CP47s.

Mechanism of swelling activation of K-Cl cotransport in inside-out vesicles of LK sheep erythrocyte membranes

1996 ◽  
Vol 270 (4) ◽  
pp. C1122-C1130 ◽  
Author(s):  
S. J. Kelley ◽  
P. B. Dunham
Keyword(s):  
Sheep Erythrocyte ◽  
Maximum Velocity ◽  
Erythrocyte Membranes ◽  
Second Step ◽  
Apparent Affinity ◽  
Specific Change ◽  
State Process ◽  
Rate Limiting ◽  
Inside Out ◽  
Mechanical Change

Stimulation by swelling of K-Cl cotransport was studied in inside-out vesicles (IOVs) made from membranes of LK sheep erythrocytes. The purpose was to understand this stimulation in terms of the three-state process proposed for regulation of the cotransporter (P.B. Dunham, J. Klimczak, and P.J. Logue. J. Gen. Physiol. 101: 733-765, 1993). The first step in this process, A --> B, is rate limiting and controlled by transphosphorylation reactions. The second step, B --> C, is fast; its control is unknown. Predictions were that maximum velocity (Jmax) of cotransport increases with A --> B and concentration at one-half Jmax (K1/2) of K+ as a substrate decreases with B --> C. We tested the hypothesis that most transporters in IOVs are in the B state and that swelling activates cotransport in vesicles by the B --> C conversion. In accordance with this hypothesis, swelling should activate K+ influx with no discernable delay. It did. K1/2 for K+ should decrease with swelling and Jmax should not change. K1/2 decreased 10-fold, and Jmax did not change. Inhibitors of transphosphorylation, reactions of A --> B, should not affect K+ flux into IOVs, and they did not. The results support the hypothesis: swelling activation of K+ flux into IOVs corresponds to B --> C. A mechanical change in the membrane causes a specific change in the cotransporter: an increase in apparent affinity for K+.

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