Claudia Büchel

Claudia Büchel
Goethe-Universität Frankfurt am Main · Institute of Molecular Biosciences

About

128
Publications
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Publications

Publications (128)
Article
In diatoms, light-harvesting processes take place in a specific group of proteins, called fucoxanthin chlorophyll a/c proteins (FCP). This group includes many members and represents the major characteristic of the diatom photosynthetic apparatus, with specific pigments bound (chlorophyll c, fucoxanthin, diadino- and diatoxanthin besides chlorophyll...
Article
Diatoms are a group of marine algae that are responsible for a significant part of global oxygen production. Adapted to the life in aqueous environment dominated by the blue-green light, their major light-harvesting antennae-fucoxhanthin-chlorophyll protein complexes (FCPs)-exhibit different pigment composition than that of plants. Despite extensiv...
Article
Full-text available
Photosynthetic light-harvesting antennae are pigment-binding proteins that perform one of the most fundamental tasks on Earth, capturing light and transferring energy that enables life in our biosphere. Adaptation to different light environments led to the evolution of an astonishing diversity of light-harvesting systems. At the same time, several...
Article
A plant-like cryptochrome of diatom microalgae, CryP, acts as a photoreceptor involved in transcriptional regulation. It contains FAD and 5,10-methenyltetrahydrofolate as chromophores. Here, we demonstrate that the unstructured C-terminal extension (CTE) of CryP has an influence on the redox state of the flavin. In CryP lacking the CTE, the flavin...
Preprint
Full-text available
In thylakoid membranes, Photosystem II monomers from the stromal lamellae contain the subunits PsbS and Psb27 (PSIIm-S/27), while Photosystem II monomers from granal regions (PSIIm) lack these subunits. Here, we have isolated and characterised these two types of Photosystem II complexes. The PSIIm-S/27 showed enhanced fluorescence, the near-absence...
Article
Full-text available
Diatoms are a large group of marine algae that are responsible for about one-quarter of global carbon fixation. Light-harvesting complexes of diatoms are formed by the fucoxanthin chlorophyll a/c proteins and their overall organization around core complexes of photosystem (PS) I and II is unique in the plant kingdom. Using cryo-electron tomography,...
Article
Fucoxanthin chlorophyll-binding proteins (FCPs) are the major light-harvesting complexes of diatoms. In this work, FCPs isolated from Cyclotella meneghiniana have been studied by means of optically detected magnetic resonance (ODMR) and time-resolved electron paramagnetic resonance (TR-EPR), with the aim to characterize the photoprotective mechanis...
Article
Diatoms are a major group of algae, responsible for a quarter of the global primary production on our planet. Their adaptation to marine environment is ensured by their light-harvesting antenna – the fucoxanthin-chlorophyll protein (FCP) complex, which absorbs strongly in the blue–green spectral region. Although these essential proteins have been t...
Article
Diatoms play a key role in assessing the ecotoxicology of metals and are already part of several national and international guidelines and regulations. Data on metal uptake and its correlation with a natural metal composition of the diatoms are mostly lacking on a cellular basis - mainly due to the lack of a suitable method on both the preparation...
Chapter
Diatoms contain antenna proteins called fucoxanthin-chlorophyll-proteins (FCP) that belong to the huge family of intrinsic light-harvesting complex proteins (LHCs). In comparison to higher plants, many more polypeptides are present, that are sorted into three major groups: Lhcf that constitute all major antenna complexes, Lhcr that are only found a...
Article
Full-text available
Despite the ecological relevance of diatoms, many aspects of their photosynthetic machinery remain poorly understood. Diatoms differ from the green lineage of oxygenic organisms by their photosynthetic pigments and light-harvesting complex (Lhc) proteins, the latter of which are also called fucoxanthin-chlorophyll proteins (FCP). These are composed...
Article
Vibronic coupling between molecules has been recently discussed to play an important role in photosynthetic functions. Furthermore, this type of coupling between electronic states has been suggested to define photophysical properties of chlorophylls, a family of photosynthetic molecules. However, experimental investigation of vibronic coupling pres...
Article
Light-harvesting systems in a group of microalgae differ from those in plants
Article
Nanoplastics (NP) and microplastics (MP) accumulate in our environment as a consequence of the massive consumption of plastics. Huge knowledge-gaps exist regarding uptake and fate of plastic particles in micro- and nano-dimensions in humans as well as on their impact on human health. This study investigated the transport and effects of 50 nm and 0....
Article
The most challenging part in performing a single cell ICP-MS (sc-ICP-MS) approach is the sample preparation, in particular the reduction of the ionic background. This step is, in many cases, time-consuming and required for each sample separately. Furthermore, sc-ICP-MS measurements are mostly carried out "manually", given the fact that present syst...
Article
Besides the so-called ‘green lineage’ of eukaryotic photosynthetic organisms that include vascular plants, a huge variety of different algal groups exist that also harvest light by means of membrane intrinsic light harvesting proteins (Lhc). The main taxa of these algae are the Cryptophytes, Haptophytes, Dinophytes, Chromeridae and the Heterokonts,...
Article
The ecological success of diatoms, key contributors to photosynthesis, is partly based on their ability to perfectly balance efficient light harvesting and photoprotection. Diatoms contain higher numbers of antenna proteins than vascular plants for light harvesting and for photoprotection. These proteins are arranged in fucoxanthin-chlorophyll prot...
Chapter
The light-harvesting proteins of oxygenic photosynthesis include mainly the phycobiliproteins and the light-harvesting complex (Lhc) family. Whereas the former are found in cyanobacteria, glaucophytes, red algae and cryptophytes, the latter are present in all eukaryotic organisms. Phycobiliproteins covalently bind bilins and are arranged in phycobi...
Article
Genetic engineering of Phaeodactylum tricornutum as a model organism for diatoms is the basis of molecular and biochemical research, and can also be used in biotechnological approaches. So far, integration of foreign DNA into the genome happens randomly by non-homologous end joining (NHEJ), if the classical method of particle bombardment is used, w...
Article
Diatoms show a special organisation of their plastid membranes, such that their thylakoids span the entire plastid in bands of three. While in higher plants the interaction of the light harvesting complex II and photosystem II with divalent cations (especially Mg²⁺) was found to take part in the interplay of electrostatic attraction and repulsion i...
Article
Transient absorption spectroscopy has been applied to investigate the energy dissipation mechanisms in the nonameric fucoxanthin-chlorophyll-a,c-binding protein FCPb of the centric diatom Cyclotella meneghiniana. FCPb complexes in their unquenched state were compared with those in two types of quenching environments, namely aggregation-induced quen...
Article
Full-text available
Diatoms possess fucoxanthin chlorophyll proteins (FCP) as light-harvesting systems. These membrane intrinsic proteins bind fucoxanthin as major carotenoid and Chl c as accessory chlorophyll. The relatively high sequence homology to higher plant light-harvesting complex II gave rise to the assumption of a similar overall structure. From centric diat...
Article
Full-text available
Strong excitonic interactions are a key design strategy in photosynthetic light harvesting, expanding the spectral cross-section for light absorption and creating considerably faster and more robust excitation energy transfer. These molecular excitons are a direct result of exceptionally densely packed pigments in photosynthetic proteins. The main...
Article
Diatoms, albeit being only distantly related with higher plants, harbour a plant-like cryptochrome (CryP) that was proposed to act as a photoreceptor required for the regulation of some photosynthetic proteins. Plant cryptochromes are involved in the regulation of developmental processes relevant only to multicellular organisms. Their role in the u...
Article
Comparative proteome analysis of subcellular compartments like thylakoid membranes and their associated supercomplexes can deliver important in-vivo information on the molecular basis of physiological functions which go far beyond to that what can be learnt from transcriptional-based gene expression studies. For instance, the finding that light int...
Article
The cryptochrome − photolyase family (CPF) consists of homologous flavoproteins having completely different functions involving DNA repair, circadian rhythm and/or photoreception. From the original photolyases, working either as (6-4) or cyclobutane pyrimidine dimer photolyases, the animal- and plant-type cryptochromes, respectively, evolved and al...
Article
Full-text available
Haberlea rhodopensis is a homoiochlorophyllous desiccation-tolerant plant growing mostly in shaded rock rifts below the trees at very low light intensity. These shade plants are very sensitive to photoinhibition and do not survive desiccation at irradiance of 350 μmol m−2 s−1, whereas plants growing on the top of rocks exposed to full sunlight (sun...
Article
Diatoms possess special light-harvesting proteins involved in the photoprotection mechanism called non-photochemical quenching (NPQ). These Lhcx proteins were shown to be subunits of trimeric fucoxanthin-chlorophyll complexes (FCPa) in centric diatoms, but their mode of action is still unclear. Here we investigated the influence of Fcp6, an ortholo...
Article
Phaeodactylum tricornutum like other diatoms synthesizes fucoxanthin and diadinoxanthin as major carotenoid end products. The genes involved have recently been assigned for early pathway steps. Beyond β-carotene, only gene candidates for β-carotene hydroxylase, zeaxanthin epoxidase and zeaxanthin de-epoxidase have been proposed from the available g...
Article
Full-text available
The changes in the content of some proteins involved in the light reactions of photosynthesis were examined during desiccation and after rehydration of shade and sun H. rhodopensis plants. Desiccation of plants to air-dry state resulted in a decreased level of the main proteins of both photosystems. The level of PSI reaction centre protein, PsaB wa...
Article
Full-text available
PSII occurs in different forms and supercomplexes in thylakoid membranes. Using a transplastomic strain of Nicotiana tabacum histidine tagged on the subunit PsbE, we have previously shown that a mild extraction protocol with β-dodecylmaltoside enriches PSII characteristic of lamellae and grana margins. Here, we characterize residual granal PSII tha...
Article
Diatoms accumulate triacylglycerols (TAGs) as storage lipids, but the knowledge about the molecular mechanisms of lipid metabolism is still sparse. Starting from a partial sequence for a putative TAG-lipase of the diatom Phaeodactylum tricornutum retrieved from the data bases, we have identified the full length coding sequence, tgl1. The gene encod...
Poster
PSII occurs in different forms and supercomplexes in thylakoid membranes. Using a transplastomic strain of Nicotiana tabacum histidine tagged on the subunit PsbE, we have previously shown that a mild extraction protocol with β-dodecylmaltoside enriches PSII characteristic of lamellae and grana margins. Here, we characterize residual grana PSII that...
Article
Full-text available
Knowledge of host-symbiont specificity and acclimatization capacity of corals is crucial for understanding implications of environmental change. Whilst some corals have been shown to associate with a number of symbionts that may comprise different physiologies, most corals associate with only one dominant Symbiodinium species at a time. Coral commu...
Article
The carotenoid fucoxanthin found in the Phaeophyceae and Bacillariophyceae (diatoms) is an antioxidative agent used as a nutraceutical for humans. In algae, terpenoids (including carotenoids) are synthesized via the 1-deoxy-d-xylulose 5-phosphate synthase pathway. The gene dxs encoding a 1-deoxy-d-xylulose 5-phosphate synthase was identified in the...
Article
Full-text available
Mesophotic coral ecosystems receive increasing attention owing to their potential as deep coral refuges in times of global environmental change. Here, the mechanisms of coral holobiont photoacclimatization over a 60 m depth gradient in the central Red Sea were examined for the four coral genera Porites, Leptoseris, Pachyseris, and Podabacia. Genera...
Article
Full-text available
Energy transfer processes and coherent phenomena in the fucoxanthin–chlorophyll protein complex, which is responsible for the light harvesting function in marine algae diatoms, were investigated at 77 K by using two-dimensional electronic spectroscopy. Experiments performed on femtosecond and picosecond timescales led to separation of spectral dyna...
Article
Full-text available
Many coral species display changing distribution patterns across coral reef depths. While changes in the underwater light field and the ability to associate with different photosynthetic symbionts of the genus Symbiodinium explain some of the variation, the limits to physiological plasticity are unknown for most corals. In the central Red Sea, colo...
Article
Fucoxanthin–chlorophyll protein (FCP) is the key molecular complex performing the light-harvesting function in diatoms, which, being a major group of algae, are responsible for up to one quarter of the total primary production on Earth. These photosynthetic organisms contain an unusually large amount of the carotenoid fucoxanthin, which absorbs the...
Article
The consequences of ketocarotenoid production in transgenic tobacco (Nicotiana tabacum) plants expressing a Chlamydomonas reinhardtii gene encoding a β-carotene ketolase were examined concerning the functionality of the photosynthetic apparatus. T1 plants produced less photosynthetic pigments per dry weight, but Chl a/Chl b ratios remained unchange...
Chapter
Diatoms possess membrane-intrinsic light-harvesting proteins, called fucoxanthin-chlorophyll-proteins (FCPs) that, based on their protein sequences, are related to higher plant light-harvesting complexes (LHCs). FCPs differ from LHCs in overall organization around the photosystems, and in that fucoxanthin and chlorophyll c (Chl c) serve as the diat...
Article
Photosynthetic eukaryotes exhibit very different light-harvesting proteins, but all contain membrane-intrinsic light-harvesting complexes (Lhcs), either as additional or sole antennae. Lhcs non-covalently bind chlorophyll a and in most cases another chlorophyll, as well as very different carotenoids, depending on the taxon. The proteins fall into t...
Article
Photosynthetic organisms have developed vital strategies which allow them to switch from a light-harvesting to an energy dissipative state at the level of the antenna system in order to survive the detrimental effects of excess light illumination. These mechanisms are particularly relevant in diatoms, which grow in highly fluctuating light environm...
Chapter
Fucoxanthin-chlorophyll proteins (FCPs) of diatoms are divided into three groups, the main light harvesting antennas Lhcf, the photosystem I-specific Lhcr, and Lhcx involved in photoprotection. All are closely related to higher plant light harvesting complexes (LHCs) when comparing sequences, albeit smaller and more hydrophobic. However, pigmentati...
Data
Full-text available
In this work we have applied picosecond and steady-state fluorescence measurements to study excitation energy transfer and trapping in intact Cyclotella meneghiniana diatom cells grown at different light intensities. Different excitation and detection wavelengths were used to discriminate between Photosystem I and II (PSI and PSII) kinetics and to...
Article
Diatoms possess several genes for proteins of the cryptochrome / photolyase family. A typical sequence for a plant cryptochrome was not found in our analysis of the Phaeodactylum tricornutum genome, but one protein grouped with higher plant and green algal cryptochromes. This protein, CryP, binds flavin adenine dinucleotide (FAD) and 5,10-methenylt...
Article
Diatoms, which are primary producers in the oceans, can rapidly switch on/off efficient photoprotection to respond to fast light-intensity changes in moving waters. The corresponding thermal dissipation of excess-absorbed-light energy can be observed as non-photochemical quenching (NPQ) of chlorophyll a fluorescence. Fluorescence-induction measurem...
Article
Light-harvesting in fucoxanthin-chlorophyll protein (FCP) of diatoms is performed by a cluster of chromophores: chlorophylls a (Chl a), chlorophylls c2 (Chl c2), and carotenoids fucoxanthins. It is well-known that energy captured by fucoxanthin is transferred to Chl a on a subpicosecond time scale. However, the energy flow channel connecting Chl c2...
Article
In this study, we demonstrate the selective in vivo detection of diadinoxanthin (DD) and diatoxanthin (DT) in intact Cyclotella cells using resonance Raman spectroscopy. In these cells, we were able to assess both the content of DD and DT carotenoids relative to chlorophyll and their conformation. In addition, the sensitivity and selectivity of the...
Article
Full-text available
Diatoms are characterized by very efficient photoprotective mechanisms where the excess energy is dissipated as heat in the main antenna system constituted by fucoxanthin-chlorophyll (Chl) protein complexes (FCPs). We performed Stark fluorescence spectroscopy on FCPs in their light-harvesting and energy dissipating states. Our results show that two...
Article
Full-text available
Photosystem II has been purified from a transplastomic strain of Nicotiana tabacum according to two different protocols. Using the procedure described in Piano et al. (Photosynth Res 106:221-226, 2010) it was possible to isolate highly active PSII composed of monomers and dimers but depleted in their PsbS protein content. A "milder" procedure than...
Article
Although the major light harvesting complexes of diatoms, called FCPs (Fucoxanthin chlorophyll a/c binding proteins), are related to the cab proteins of higher plants, the structures of these light harvesting protein complexes are much less characterized. Here, a structural/functional model for the "core" of FCP, based on the sequence homology with...
Article
The (auto)fluorescence from three diatom strains, Cyclotella meneghiniana (Cm), Phaeodactylum tricornutum 1a (Pt1a) and Phaeodactylum UTex (PtUTex), has been imaged in vivo to sub-micron resolution using confocal laser scanning fluorescence (CLSF) microscopy. The diatoms are excited at 473 nm and 532 nm, energy primarily absorbed by the carotenoid...
Article
Diatoms are major contributors to the photosynthetic productivity of marine phytoplankton. In these organisms, fucoxanthin-chlorophyll proteins (FCPs) serve as light-harvesting proteins. We have explored the FCP complexes in Phaeodactylum tricornutum under low light (LL) and high light (HL) conditions. Sub-fractionating the pool of major FCPs yield...
Article
In this work we have applied picosecond and steady-state fluorescence measurements to study excitation energy transfer and trapping in intact Cyclotella meneghiniana diatom cells grown at different light intensities. Different excitation and detection wavelengths were used to discriminate between Photosystem I and II (PSI and PSII) kinetics and to...
Article
In this work we present an optically detected magnetic resonance (ODMR) study on the triplet states populated under illumination in the isolated fucoxanthin-chlorophyll light-harvesting complex from the diatom Cyclotella meneghiniana. Evidence for the quenching of chlorophyll triplet states by fucoxanthin is provided, showing that this carotenoid i...
Article
Full-text available
The biosynthesis pathway to diadinoxanthin and fucoxanthin was elucidated in Phaeodactylum tricornutum by a combined approach involving metabolite analysis identification of gene function. For the initial steps leading to β-carotene, putative genes were selected from the genomic database and the function of several of them identified by genetic pat...
Article
Full-text available
Analysis of photosystem I (PSI) complexes from Cyclotella meneghiniana cultured under different growth conditions led to the identification of three groups of antenna proteins, having molecular weights of around 19, 18, and 17 kDa. The 19-kDa proteins have earlier been demonstrated to be more peripherally bound to PSI, and their amount in the PSI c...
Article
Fucoxanthin-chlorophyll complexes (FCP) from the centric diatom Cyclotella meneghiniana were isolated and the trimeric FCPa complex was reconstituted into liposomes at different lipid to Chl a ratios. The fluorescence yield of the complexes in different environments was calculated from room temperature fluorescence emission spectra and compared to...