22 Result(s)
within
English
Biochemistry, general
Klaas J. Hellingwerf
Article
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Article
Open AccessExploring the low photosynthetic efficiency of cyanobacteria in blue light using a mutant lacking phycobilisomes
The ubiquitous chlorophyll a (Chl a) pigment absorbs both blue and red light. Yet, in contrast to green algae and higher plants, most cyanobacteria have much lower photosynthetic rates in blue than in red light. ...
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Open AccessBlue light reduces photosynthetic efficiency of cyanobacteria through an imbalance between photosystems I and II
Several studies have described that cyanobacteria use blue light less efficiently for photosynthesis than most eukaryotic phototrophs, but comprehensive studies of this phenomenon are lacking. Here, we study t...
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Open AccessSpectrally decomposed dark-to-light transitions in Synechocystis sp. PCC 6803
Photosynthetic activity and respiration share the thylakoid membrane in cyanobacteria. We present a series of spectrally resolved fluorescence experiments where whole cells of the cyanobacterium Synechocystis sp....
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Tryptophan fluorescence as a reporter for structural changes in photoactive yellow protein elicited by photo-activation
Light-activation of photoactive yellow protein (PYP) is followed by a series of dynamical transitions in the structure of the protein. Tryptophan fluorescence is well-suited as a tool to study selected aspects...
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Is the photoactive yellow protein a UV-B/blue light photoreceptor?
UV light below 300 nm is shown to generate the first photocycle intermediate in the blue light photoreceptor Photoactive Yellow Protein. Fluorescence and ultrafast transient absorption measurements indicate tw...
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Binding, tuning and mechanical function of the 4-hydroxy-cinnamic acid chromophore in photoactive yellow protein
The bacterial photoreceptor protein photoactive yellow protein (PYP) covalently binds the chromophore 4-hydroxy coumaric acid, tuning (spectral) characteristics of this cofactor. Here, we study this binding an...
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Chromophore composition of a heterologously expressed BLUF-domain
Upon heterologous expression of the BLUF (for: Blue-Light sensing Using Flavin) domain from AppA, a transcriptional anti-repressor from Rhodobacter sphaeroides, in Escherichia coli, photoactive holo-protein is fo...
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Early molecular events in the photoactive yellow protein: role of the chromophore photophysics
We report a comparative study of the isomerization reaction in native and denatured photoactive yellow protein (PYP) and in various chromophore analogues in their trans deprotonated form. The excited-state relaxa...
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Tryptophan fluorescence monitors structural changes accompanying signalling state formation in the photocycle of photoactive yellow protein
Photoactive yellow protein, a small, water-soluble blue-light absorbing photoreceptor protein from Ectothiorhodospira (Halorhodospira) halophila has a structure with two hydrophobic cores, of which the main one h...
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Light-induced behavioral responses (`phototaxis') in prokaryotes
Light-induced sensory responses are among the oldest scientific observations on bacterial behavior. Various types of response have been characterized physiologically in detail. However, the molecular basis of ...
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Phototransformation of green fluorescent protein with UV and visible light leads to decarboxylation of glutamate 222
Wild type green fluorescent protein (GFP) from Aequorea victoria absorbs predominantly at 398 nm. Illumination with UV (254 nm) or visible (390 nm) light transforms this state (GFP398) into one absorbing at 483 n...
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Article
Alkalispirillum mobile gen. nov., spec. nov., an alkaliphilic non-phototrophic member of the Ectothiorhodospiraceae
From cultures of the anoxygenic phototroph Halorhodospira halophila SL-1, an aerobic, gram-negative spirillum was isolated. This moderately halophilic, alkaliphilic bacterium was motile by means of a single pola...
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Characterization and transcriptional regulation of the Synechocystis PCC 6803, petH gene, encoding ferredoxin-NADP+ oxidoreductase: involvement of a novel type of divergent operator
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Structural and dynamic changes of photoactive yellow protein during its photocycle in solution
Light irradiation of photoactive yellow protein (PYP) induces a photocycle, in which red-shifted (pR) and blue-shifted (pB) intermediates have been characterized. An NMR study of the long-lived pB intermediate...
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Characterization and transcriptional regulation of the Synechocystis PCC 6803 petH gene, encoding ferredoxin-NADP+ oxidoreductase: involvement of a novel type of divergent operator
The petH gene, encoding ferredoxin-NADP+ oxidoreductase (FNR), has been characterised in the unicellular cyanobacterium Synechocystis PCC 6803. Its product, FNR, was heterologously produced and functionally chara...
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Effect of nitrogen sources on the regulation of extracellular lipase production in Acinetobacter calcoaceticus strains
Extracellular lipase production and lipA expression were studied in A.calcoaceticus strains in relation to the nitrogen sources. Addition of casamino-acids or tryptone improved 2–3 times lipase yield as compared ...
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Article
Physiological regulation of competence induction for natural transformation in Acinetobacter calcoaceticus
Acinetobacter calcoaceticus induced competence for natural transformation maximally after dilution of a stationary culture into fresh medium. Competence was gradually lost during prolonged exponential growth and...
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A Kdp-like, high-affinity, K+-translocating ATPase is expressed during growth of Rhodobacter sphaeroides in low potassium media
Cells of the purple non-sulphur bacterium Rhodobacter sphaeroides express a high-affinity K+ uptake system when grown in media with low K+ concentrations. Antibodies againts the catalytic KdpB protein or the whol...
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Reaction centers fromRhodopseudomonas sphaeroides in reconstituted phospholipid vesicles. II. Light-induced proton translocation
Unidirectional light-dependent proton translocation was demonstrated in a suspension of reconstituted reaction center (RC) vesicles supplemented with cytochromec and 2,3-dimethoxy-5-methyl-1,4-benzoquinone (UQ0),...
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Reaction centers fromRhodopseudomonas sphaeroides in reconstituted phospholipid vesicles. I. Structural studies
Reaction centers (RCs) fromRhodopseudomonas sphaeroides were reconstituted into asolectin vesicles by cosonication. Equilibrium centrifugation on sucrose gradients showed that the vesicles were homogeneous in den...
