scholarly journals Organization of the photosystem II centers and their associated antennae in the thylakoid membranes: a comparative ultrastructural, biochemical, and biophysical study of Chlamydomonas wild type and mutants lacking in photosystem II reaction centers.

1980 ◽  
Vol 87 (3) ◽  
pp. 728-735 ◽  
Author(s):  
F A Wollman ◽  
J Olive ◽  
P Bennoun ◽  
M Recouvreur
Keyword(s):  
Photosystem Ii ◽  
Fluorescence Analysis ◽  
Thylakoid Membranes ◽  
Reaction Centers ◽  
Type Number ◽  
Wild Type ◽  
Light Harvesting Complexes ◽  
Biophysical Study ◽  
In The Wild ◽  
Type C

We investigated the ultrastructure of thylakoid membranes that lacked either some or all of their Photosystem II centers in the F34SU3 and F34 mutants of Chlamydomonas reinhardtii. We obtained the following results: (a) There are no particles of the 160-A size class on the EF faces of the thylakoids in the absence of Photosystem II centers (as in F34); the F34SU3 contains 50% of the wild-type number of PSII centers and EF particles. (b) The density of the particles on the PF faces of the thylakoids is higher in the mutants than in the wild type. (c) The fluorescence analysis shows that the organization of the pigments is the same regardless of whether 50% of the PSII centers are temporarily inactivated (by preilluminating the wild type) or are actually missing from the thylakoid membrane (F34SU3). Our results, therefore, support a model in which: (a) each 160-A EF particle has only one PSII center surrounded by light-harvesting complexes and (b) part of the PSH antenna is associated with 80-A PF particles in both of the mutants and the wild type.

scholarly journals Caenorhabditis elegans triple null mutant lacking UDP-N-acetyl-D-glucosamine:α-3-D-mannoside β1,2-N-acetylglucosaminyltransferase I

2004 ◽  
Vol 382 (3) ◽  
pp. 995-1001 ◽  
Author(s):  
Shaoxian ZHU ◽  
Andrew HANNEMAN ◽  
Vernon N. REINHOLD ◽  
Andrew M. SPENCE ◽  
Harry SCHACHTER
Keyword(s):  
Caenorhabditis Elegans ◽  
Chromosome Number ◽  
Null Mutant ◽  
Wild Type ◽  
Knock Out ◽  
C Elegans ◽  
In The Wild ◽  
Wild Type Worm ◽  
Type C ◽  
Nematode Worm

We have previously reported, from the nematode worm Caenor-habditis elegans, three genes (gly-12, gly-13 and gly-14) encoding enzymically active UDP-N-acetyl-D-glucosamine:α-3-D-mannoside β1,2-N-acetylglucosaminyltransferase I (GnT I), an enzyme essential for hybrid, paucimannose and complex N-glycan synthesis. We now describe a worm with null mutations in all three GnT I genes, gly-14 (III);gly-12 gly-13 (X) (III and X refer to the chromosome number). The triple-knock-out (TKO) worms have a normal phenotype, although they do not express GnT I activity and do not synthesize 31 paucimannose, complex and fucosylated oligomannose N-glycans present in the wild-type worm. The TKO worm has increased amounts of non-fucosylated oligomannose N-glycan structures, a finding consistent with the site of GnT I action. Five fucosylated oligomannose N-glycan structures were observed in TKO, but not wild-type, worms, indicating the presence of unusual GnT I-independent fucosyltransferases. It is concluded that wild-type C. elegans makes a large number of GnT I-dependent N-glycans that are not essential for normal worm development under laboratory conditions. The TKO worm may be more susceptible to mutations in other genes, thereby providing an approach for the identification of genes that interact with GnT I.

scholarly journals A ς54 Activator Protein Necessary for Spore Differentiation within the Fruiting Body ofMyxococcus xanthus

2000 ◽  
Vol 182 (9) ◽  
pp. 2438-2444 ◽  
Author(s):  
Lisa Gorski ◽  
Thomas Gronewold ◽  
Dale Kaiser
Keyword(s):  
Fruiting Body ◽  
Time Course ◽  
Type Number ◽  
Wild Type ◽  
Activator Proteins ◽  
Antibody Expression ◽  
Body Development ◽  
Fruiting Body Development ◽  
In The Wild ◽  
Dna Fragment

ABSTRACT Insertion of an internal DNA fragment into the act1gene, which encodes one of several ς54-activator proteins in Myxococcus xanthus, produced a mutant defective in fruiting body development. While fruiting-body aggregation appears normal in the mutant, it fails to sporulate (<10−6 the wild-type number of viable spores). The A and C intercellular signals, which are required for sporulation, are produced by the mutant. But, while it produces A-factor at levels as high as that of the wild type, the mutant produces much less C-signal than normal, as measured either by C-factor bioassay or by the total amount of C-factor protein detected with specific antibody. Expression of three C-factor-dependent reporters is altered in the mutant: the level of expression of Ω4414 is about 15% of normal, and Ω4459 and Ω4403 have alterations in their time course. Finally, the methylation of FrzCD protein is below normal in the mutant. It is proposed that Act1 protein responds to C-signal reception by increasing the expression of the csgAgene. This C-signal-dependent increase constitutes a positive feedback in the wild type. The act1 mutant, unable to raise the level of csgA expression, carries out only those developmental steps for which a low level of C-signaling is adequate.

Lipids affect the charge stabilization in wild-type and mutant reaction centers of Rhodobacter sphaeroides R-26

1999 ◽  
Vol 26 (5) ◽  
pp. 465 ◽  
Author(s):  
László Nagy ◽  
Elfrida Fodor ◽  
Júlia Tandori ◽  
László Rinyu ◽  
Tibor Farkas
Keyword(s):  
Electron Transfer ◽  
Rhodobacter Sphaeroides ◽  
Electrostatic Interactions ◽  
Reaction Centers ◽  
Wild Type ◽  
Photosynthetic Membrane ◽  
Protein Ratio ◽  
Intracytoplasmic Membranes ◽  
In The Wild ◽  
Charge Stabilization

The effect of lipids on stabilization of electrons on the secondary quinone was studied in reaction centers (RC) of herbicide-sensitive and -resistant (L229Ile → Met) Rhodobacter sphaeroides R-26. The lipid concentration and the lipid/protein ratio of the intracytoplasmic membranes (ICM) were larger in the mutant RCs than in the wild-type. The free energy changes of Q A – Q B → Q A Q B – electron transfer were ΔG 0 = –57 meV, –69 meV, –85 meV for the wild-type and ΔG 0 = 0 meV, –15 meV, –46 meV for the mutant at pH = 8.0, in detergent, liposome and ICM, respectively. The differences in the stabilization energies of both strains decreased from the detergent via proteoliposome to chromatophore. We conclude that the energetics of the interquinone electron transfer depends on the environment of the reaction center. The steric and/or electrostatic interactions of the environment and Q B pocket can modulate the energetics of the charge stabilization over large distances. The interaction may have crucial importance on coupling the electron transport in the photosynthetic membrane to the anabolic/catabolic processes taking place in the cells.

Assignment of the QyAbsorbance Bands of Photosystem II Chromophores by Low-Temperature Optical Spectroscopy of Wild-Type and Mutant Reaction Centers†

Biochemistry ◽  
2000 ◽  
Vol 39 (47) ◽  
pp. 14583-14594 ◽  
Author(s):  
David H. Stewart ◽  
Peter J. Nixon ◽  
Bruce A. Diner ◽  
Gary W. Brudvig
Keyword(s):  
Low Temperature ◽  
Photosystem Ii ◽  
Optical Spectroscopy ◽  
Reaction Centers ◽  
Wild Type

scholarly journals Chloramphenicol enhances Photosystem II photodamage in intact cells of the cyanobacterium Synechocystis PCC 6803

2020 ◽  
Vol 145 (3) ◽  
pp. 227-235
Author(s):  
Sandeesha Kodru ◽  
Ateeq ur Rehman ◽  
Imre Vass
Keyword(s):  
Protein Synthesis ◽  
Photosystem Ii ◽  
Superoxide Production ◽  
Protein Synthesis Inhibitor ◽  
Wild Type ◽  
Protein Synthesis Inhibitors ◽  
Synthesis Inhibitor ◽  
Intact Cells ◽  
In The Wild ◽  
Pcc 6803

Abstract The effect of chloramphenicol, an often used protein synthesis inhibitor, in photosynthetic systems was studied on the rate of Photosystem II (PSII) photodamage in the cyanobacterium Synechocystis PCC 6803. Light-induced loss of PSII activity was compared in the presence of chloramphenicol and another protein synthesis inhibitor, lincomycin, by measuring the rate of oxygen evolution in Synechocystis 6803 cells. Our data show that the rate of PSII photodamage was significantly enhanced by chloramphenicol, at the usually applied 200 μg mL−1 concentration, relative to that obtained in the presence of lincomycin. Chloramphenicol-induced enhancement of photodamage has been observed earlier in isolated PSII membrane particles, and has been assigned to the damaging effect of chloramphenicol-mediated superoxide production (Rehman et al. 2016, Front Plant Sci 7:479). This effect points to the involvement of superoxide as damaging agent in the presence of chloramphenicol also in Synechocystis cells. The chloramphenicol-induced enhancement of photodamage was observed not only in wild-type Synechocystis 6803, which contains both Photosystem I (PSI) and PSII, but also in a PSI-less mutant which contains only PSII. Importantly, the rate of PSII photodamage was also enhanced by the absence of PSI when compared to that in the wild-type strain under all conditions studied here, i.e., without addition and in the presence of protein synthesis inhibitors. We conclude that chloramphenicol enhances photodamage mostly by its interaction with PSII, leading probably to superoxide production. The presence of PSI is also an important regulatory factor of PSII photodamage most likely via decreasing excitation pressure on PSII.

scholarly journals Comparative analysis of the biogenesis of photosystem II in the wild-type and Y-1 mutant of Chlamydomonas reinhardtii.

1988 ◽  
Vol 106 (3) ◽  
pp. 609-616 ◽  
Author(s):  
P Malnoë ◽  
S P Mayfield ◽  
J D Rochaix
Keyword(s):  
Photosystem Ii ◽  
Chlamydomonas Reinhardtii ◽  
Oxygen Evolving Complex ◽  
Wild Type ◽  
Plastid Development ◽  
Photosynthetic System ◽  
In The Wild ◽  
Steady State Levels ◽  
Chloroplast Mrna ◽  
Oxygen Evolving

Expression of the genes of the photosystem II (PSII) core polypeptides D1 and D2, of three proteins of the oxygen evolving complex of PSII and of the light harvesting chlorophyll a/b binding proteins (LHCP) has been compared in wild-type (wt) and in the y-1 mutant of Chlamydomonas reinhardtii. Since wt, but not y-1 cells produce a fully developed photosynthetic system in the dark, comparison of the two has allowed us to distinguish the direct effect of light from the influence of plastid development on gene expression. The PSII core polypeptides and LHCP are nearly undetectable in dark-grown y-1 cells but they accumulate progressively during light induced greening. The levels of these proteins in wt are the same in the light and the dark. The amounts of the proteins of the oxygen evolving complex do not change appreciably in the light or in the dark for both wt and y-1. Steady state levels of chloroplast mRNA encoding the core PSII polypeptides remain nearly constant in the light or the dark and are not affected by the developmental stage of the plastid. Levels of nuclear encoded mRNAs for the oxygen evolving proteins and of LHCP increase during light growth in wt and y-1. In contrast to wt, synthesis of LHCP proteins is not detectable in y-1 cells in the dark but starts immediately after transfer to light, indicating that LHCP synthesis is controlled by a light-induced factor or process. While the rates of synthesis of D1 and D2 are immediately enhanced by light in wt, this increase occurs only after a lag in y-1 and thus must be dependent on an early light-induced event in the plastid. These results show that the biosynthesis of PSII is affected by light directly, by the stage of plastid development, and by the interaction of light and events associated with plastid development.

Fluorescence Decay Kinetics of Wild Type and D2-H117N Mutant Photosystem II Reaction Centers Isolated fromChlamydomonas reinhardtii

2000 ◽  
Vol 104 (19) ◽  
pp. 4777-4781 ◽  
Author(s):  
Heather G. Johnston ◽  
Jun Wang ◽  
Stuart V. Ruffle ◽  
Richard T. Sayre ◽  
Terry L. Gustafson
Keyword(s):  
Photosystem Ii ◽  
Fluorescence Decay ◽  
Reaction Centers ◽  
Wild Type ◽  
Decay Kinetics ◽  
Fluorescence Decay Kinetics ◽  
Kinetics Of

Structural Role of Carotenoids in Photosynthetic Membranes

1996 ◽  
Vol 51 (11-12) ◽  
pp. 763-771 ◽  
Author(s):  
Andrey A Moskalenko ◽  
Navassard V Karapetyan
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Purple Bacteria ◽  
Reaction Centers ◽  
Structural Components ◽  
Light Harvesting Complexes ◽  
Photosynthetic Membranes

Besides the light-harvesting and protecting role, carotenoids are also instrumental as structural components for the assembly of light-harvesting complexes in purple bacteria and green plants, as well as for the formation of photosystem II complex. Carotenoids stabilize those pigm ent-protein complexes, but have no effect on the form ation of the reaction centers of purple bacteria and photosystem I of plants.

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