Ute C Vothknecht

Ute C Vothknecht
University of Bonn | Uni Bonn · Institute for Cellular and Molecular Botany

Prof. Dr.

About

95
Publications
12,145
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
3,496
Citations
Additional affiliations
April 2016 - present
University of Bonn
Position
  • Professor
November 2007 - present
Ludwig-Maximilians-University of Munich
Position
  • CIPSM
November 2007 - March 2016
Ludwig-Maximilians-University of Munich
Position
  • Professor

Publications

Publications (95)
Article
Precise measurements of dynamic changes in free Ca2+ concentration in the lumen of the plant endoplasmic reticulum (ER) have been lacking so far, despite increasing evidence for the contribution of this intracellular compartment to Ca2+ homeostasis and signalling in the plant cell. In this work we targeted an aequorin chimera with reduced Ca2+ affi...
Conference Paper
Full-text available
Plant-parasitic nematodes (PPNs) are among the most damaging plant pathogens that threaten current and future global food security. Most of the damage caused by PPNs is due to a small group of root-infecting sedentary endoparasitic nematodes (SEPs) that includes cyst nematodes and root-knot nematodes. Infection is initiated by an infective second-s...
Preprint
Full-text available
Jasmonates have a well-documented role in balancing the trade-off between plant growth and defense against biotic stresses. However, the role of jasmonate signaling under abiotic stress is less well studied. Here, we investigated the function of JASMONATE RESISTANT 1 ( JAR1 ) in drought stress in Arabidopsis thaliana. JAR1 converts jasmonic acid (J...
Article
Calcium ion (Ca²⁺) is a versatile signaling transducer in all eukaryotic organisms. In plants, intracellular changes in free Ca²⁺ levels act as regulators in many growth and developmental processes. Ca²⁺ also mediates the cellular responses to environmental stimuli and thus plays an important role in providing stress tolerance to plants. Ca²⁺ signa...
Article
Full-text available
Metabolic fluctuations in chloroplasts and mitochondria can trigger retrograde signals to modify nuclear gene expression. Mobile signals likely to be involved are reactive oxygen species (ROS), which can operate protein redox switches by oxidation of specific cysteine residues. Redox buffers such as the highly reduced glutathione pool serve as rese...
Preprint
Full-text available
Metabolic fluctuations in chloroplasts and mitochondria can trigger retrograde signals to modify nuclear gene expression. Mobile signals likely to be involved are reactive oxygen species (ROS), which can operate protein redox switches by oxidation of specific cysteine residues. Redox buffers such as the highly reduced glutathione pool serve as rese...
Article
Mitochondria are crucial bioenergetic organelles for providing different metabolites, including ATP, to sustain cell growth both in animals and in plants. These organelles, delimited by two membranes (outer and inner mitochondrial membranes), maintain their function by an intensive communication with other organelles as well as with the cytosol. Tr...
Article
Full-text available
Reversible phosphorylation of thylakoid proteins contributes to photoacclimation responses in photosynthetic organisms, enabling the fine-tuning of light harvesting under changing light conditions and promoting the onset of photoprotective processes. However, the precise functional role of many of the described phosphorylation events on thylakoid p...
Article
Full-text available
Chloroplasts are integral to sensing biotic and abiotic stress in plants, but their role in transducing Ca²⁺-mediated stress signals remains poorly understood1,2. Here we identify cMCU, a member of the mitochondrial calcium uniporter (MCU) family, as an ion channel mediating Ca²⁺ flux into chloroplasts in vivo. Using a toolkit of aequorin reporters...
Article
Ca ²⁺ is a potent signalling molecule that regulates many cellular processes. In cyanobacteria, Ca ²⁺ has been linked to cell growth, stress response and photosynthesis, and to the development of specialist heterocyst cells in certain nitrogen-fixing species. Despite this, the pathways of Ca ²⁺ signal transduction in cyanobacteria are poorly unders...
Preprint
Full-text available
Ca2+ is a potent signalling molecule that regulates many cellular processes. In cyanobacteria, Ca2+ has been linked to cell growth, stress response and photosynthesis, and to the development of specialist heterocyst cells in certain nitrogen-fixing species. Despite this, the pathways of calcium signal transduction in cyanobacteria are poorly unders...
Article
Full-text available
Chloroplasts require a fine-tuned control of their internal Ca2+ concentration, which is crucial for many aspects of photosynthesis and for other chloroplast-localized processes. Increasing evidence suggests that calcium regulation within chloroplasts may also influence Ca2+ signalling pathways in the cytosol. To investigate the involvement of thyl...
Chapter
Gated ion channels open or close in response to changes in membrane potential, binding of ligands at extracellular or intracellular sites, or mechanical stimuli. Many natural products including plant-derived drugs and plant and animal toxins interfere with the function of ion channels. Here we first discuss neurotoxin binding to voltage-gated ion c...
Chapter
Ion channels are formed by proteins with multiple, usually six, transmembrane domains, which as homo- or hetero-oligomers form aqueous pores that allow ions to pass between the outside and the inside of the cell according to their concentration gradient. Ion channels thus conduct ion currents in response to changes in membrane voltage (voltage-gate...
Chapter
G-protein-coupled receptors (GPCRs) as indicated by their name are coupled to trimeric G-proteins. Upon ligand binding to the receptor, the trimeric G-proteins dissociate into a Gα-subunit and a Gβ/γ-heterodimer. Both the α-subunit and the Gβ/γ-dimer then activate further signalling, for instance, by regulating the production of second messengers o...
Chapter
Plants usually contain many different secondary metabolites, but some species contain very specific subsets of secondary metabolites. The amount of the compounds and the kind of compounds vary between different cells, tissues and developmental stages and can be influenced by external stressors. This means that the enzymatic pathways have to be tigh...
Chapter
Primary metabolites are compounds that are associated with essential cellular functions. Therefore, they are very much ubiquitously found in all plants. By contrast, secondary metabolites have much more specific functions. They are often species specific and can be dispensable under many conditions. Nevertheless, the basis of most secondary metabol...
Chapter
Besides the classical groups of alkaloids, phenylpropanoids and isoprenoids, several other biosynthesis pathways produce important classes of secondary metabolites. These include especially cannabinoids and fatty acid-derived compounds.
Chapter
The presence of GPRCs in plants is still a question of debate. While G-protein coupled signalling exists, the signalling cycle is typically not activated by seven transmembrane-spanning receptors. By contrast, many plant secondary metabolites are known to affect human GPRCs. Some are very specific for a single type of receptor; however, many others...
Chapter
Alkaloids are characterized by containing a nitrogen atom, usually within a heterocyclic ring. Many are derived from aromatic amino acids, but for some also other amino acids, ornithine, spermidine, xanthosine and the terpenoids are the basic building blocks. Many well-known compounds such as caffeine, nicotine and atropine fall into this group. Th...
Chapter
Terpenes and their derivatives, the terpenoids, are synthetized from a five carbon atom isoprene unit. These units are added to each other to give rise to compounds of different complexities. The synthesis takes place either in the cytosol (MVA pathway) or within the plastids (MEP pathway). Monoterpenes, diterpenes and tetraterpenes are products fr...
Chapter
Compared to GPCRs, the set of plant-derived compounds that target ion channels appears much more limited. For voltage-gated channels, most known toxins are derived from animals such as snails, spiders and snakes. Also, many ligand-gated channels are targeted by few to none known plant-derived drugs. Nevertheless, ion channels are the target of some...
Chapter
Aromatic amino acids are produced via the shikimate pathway in the plastids, which are the precursors of phenylpropanoids. Phenylpropanoids contribute to the taste of many plant-derived food, but their interaction with the human body is in many cases not well documented. Many of these compounds act as precursors for alkaloids.
Chapter
While many of the secondary metabolites produced by plants make them unpalatable or toxic, the specific capacities of natural plant products have also been exploited by humans for a long time. In its simplest form, they have been used as spices and aroma compounds to give flavour to food. While it is rather easy to imagine this development, it is a...
Chapter
The family of GPCRs represents the most important class of pharmaceutical drug targets. In this chapter, we describe such receptors and pathways that are targets for well-known plant-derived drugs and toxins. These include adrenergic receptors, the muscarinic acetylcholine receptor (MAchR), adenosine receptors, cannabinoid receptors, dopamine- and...
Book
This textbook provides a structured, easy to understand and thorough insight into the mode of function of plant secondary metabolites in plants and humans. It explains the biosynthesis and molecular action of nicotine, cannabis, caffeine and Co, describes the effects of these drugs on signal transduction at receptors and ion channels in animals, th...
Article
The translocon on the outer membrane of mitochondria (TOM) facilitates import of nuclear encoded proteins. The principal machinery seems conserved in eukaryotes, however, divergence in composition and structure of TOM components has been observed between mammals, yeast and plants. TOM9, the plant homologue of yeast Tom22, is significantly smaller d...
Article
Full-text available
Calmodulins (CaMs) are important mediators of Ca(2+)signals that are found ubiquitously in all eukaryotic organisms. Plants contain a unique family of calmodulin-like proteins (CMLs) that exhibit greater sequence variance compared to canonical CaMs. TheArabidopsis thalianaproteins AtCML4 and AtCML5 are members of CML subfamily VII and possess a CaM...
Article
Full-text available
Calcium is used by plants as an intracellular messenger in the detection of and response to a plethora of environmental stimuli and contributes to a fine-tuned internal regulation. Interest in the role of different subcellular compartments in Ca2+ homeostasis and signalling has been growing in recent years. This work has evaluated the potential par...
Article
Full-text available
Background: Adenine nucleotide/phosphate carriers (APCs) from mammals and yeast are commonly known to adapt the mitochondrial adenine nucleotide pool in accordance to cellular demands. They catalyze adenine nucleotide - particularly ATP-Mg - and phosphate exchange and their activity is regulated by calcium. Our current knowledge about correspondin...
Article
Full-text available
Calcium is an important second messenger in eukaryotic cells that regulates many different cellular processes. To elucidate calcium regulation in chloroplasts, we identified targets of calcium-dependent phosphorylation within the stromal proteome. A 73 kDa protein was one of the most dominant proteins undergoing phosphorylation in a calcium-depende...
Article
Full-text available
Calcium plays an important role in the regulation of several chloroplast processes. However, very little is still understood about the calcium fluxes or calcium-binding proteins present in plastids. Indeed, classical EF-hand containing calcium-binding proteins appears to be mostly absent from plastids. In the present study we analyzed the stroma fr...
Article
Full-text available
Matrix enzymes are imported into peroxisomes and glyoxysomes, a subclass of peroxisomes involved in lipid mobilization. Two peroxisomal targeting signals (PTS), the C-terminal PTS1 and the N-terminal PTS2, mediate the translocation of proteins into the organelle. PTS2 processing upon import is conserved in higher eukaryotes, and in watermelon the g...
Chapter
Vipp1 (vesicle inducing protein in plastids 1) is proposed to play a role in thylakoid biogenesis. It is closely related to PspA (phage shock protein A), a bacterial protein that is induced under stress conditions. Despite its discovery a decade ago and extensive analysis in cyanobacteria, green algae and higher plants, the precise role of Vipp1 in...
Article
Full-text available
VESICLE-INDUCING PROTEIN IN PLASTIDS1 (VIPP1), proposed to play a role in thylakoid biogenesis, is conserved in photosynthetic organisms and is closely related to Phage Shock Protein A (PspA), which is involved in plasma membrane integrity in Escherichia coli. This study showed that chloroplasts/plastids in Arabidopsis thaliana vipp1 knockdown and...
Article
The vesicle-inducing protein in plastids 1 (Vipp1) is an essential component for thylakoid biogenesis in cyanobacteria and chloroplasts. Vipp1 proteins share significant structural similarity with their evolutionary ancestor PspA (bacterial phage shock protein A), namely a predominantly α-helical structure, the formation of oligomeric high molecula...
Article
Full-text available
In addition to redox regulation, protein phosphorylation has gained increasing importance as a regulatory principle in chloroplasts in recent years. However, only very few chloroplast-localized protein kinases have been identified to date. Protein phosphorylation regulates important chloroplast processes such as photosynthesis or transcription. In...
Article
Programmed cell death (PCD) in plants is a prerequisite for development as well as seed and fruit production. It also plays a significant role in pathogen defense. A unique group of papain-type cysteine endopeptidases, characterized by a C-terminal endoplasmic reticulum (ER) retention signal (KDEL CysEP), is involved in plant PCD. Genes for these e...
Article
Full-text available
More than 70 years of studies have indicated that chloroplasts contain a significant amount of calcium, are a potential storage compartment for this ion, and might themselves be prone to calcium regulation. Many of these studies have been performed on the photosynthetic light reaction as well as CO(2) fixation via the Calvin-Benson-Bassham cycle, a...
Article
Full-text available
Calcium has long been acknowledged as one of the most important signalling components in plants. Many abiotic and biotic stimuli are transduced into a cellular response by temporal and spatial changes in cellular calcium concentration and the calcium-sensitive protein aequorin has been exploited as a genetically encoded calcium indicator for the me...
Article
Full-text available
This review provides a comprehensive overview of the established and emerging roles that organelles play in calcium signalling. The function of calcium as a secondary messenger in signal transduction networks is well documented in all eukaryotic organisms, but so far existing reviews have hardly addressed the role of organelles in calcium signallin...
Article
Full-text available
The role of protein phosphorylation for adjusting chloroplast functions to changing environmental needs is well established, whereas calcium signalling in the chloroplast is only recently becoming appreciated. The work presented here explores the potential cross-talk between calcium signalling and protein phosphorylation in chloroplasts and provide...
Article
Full-text available
As a key feature in oxygenic photosynthesis, thylakoid membranes play an essential role in the physiology of plants, algae, and cyanobacteria. Despite their importance in the process of oxygenic photosynthesis, their biogenesis has remained a mystery to the present day. A decade ago, vesicle-inducing protein in plastids 1 (Vipp1) was described to b...
Article
Calmodulin (CaM) is a ubiquitous sensor/transducer of calcium signals in eukaryotic organisms. While CaM mediated calcium regulation of cytosolic processes is well established, there is growing evidence for the inclusion of organelles such as chloroplasts, mitochondria and peroxisomes into the calcium/calmodulin regulation network. A number of CaM-...
Article
Chloroplasts and mitochondria are central to crucial cellular processes in plants and contribute to a whole range of metabolic pathways. The use of calcium ions as a secondary messenger in and around organelles is increasingly appreciated as an important mediator of plant cell signaling, enabling plants to develop or to acclimatize to changing envi...
Article
Full-text available
OBG-like GTPases, a subfamily of P-loop GTPases, have divers and important functions in bacteria, including initiation of sporulation, DNA replication, and protein translation. Homologs of the Bacillus subtilis spo0B GTP-binding protein (OBG) can be found in plants and algae but their specific function in these organisms has not yet been elucidated...
Article
Full-text available
In plant cells calcium-dependent signaling pathways are involved in a large array of biological processes in response to hormones, biotic/abiotic stress signals and a variety of developmental cues. This is generally achieved through binding of calcium to diverse calcium-sensing proteins, which subsequently control downstream events by activating or...
Article
Members of the AAA(+)-ATPase superfamily (ATPases associated with various cellular activities) are found in all kingdoms of life and they are involved in very diverse cellular processes, including protein degradation, membrane fusion or cell division. The Arabidopsis genome encodes approximately 140 different proteins that are putative members of t...
Article
Many metabolic processes essential for plant viability take place in mitochondria. Therefore, mitochondrial function has to be carefully balanced in accordance with the developmental stage and metabolic requirements of the cell. One way to adapt organellar function is the alteration of protein composition. Since most mitochondrial proteins are nucl...
Article
Vipp1 (vesicle inducing protein in plastids 1) is found in cyanobacteria and chloroplasts where it is essential for thylakoid formation. Arabidopsis thaliana mutant plants with a reduction of Vipp1 to about 20% of wild type content become albinotic at an early stage. We propose that this drastic phenotype results from an inability of the remaining...
Article
Full-text available
A serine/threonine protein kinase that is able to phosphorylate chloroplast-destined precursor proteins was purified from leaf extract of Arabidopsis thaliana and was identified by mass spectrometry. The protein kinase, encoded by AT2G17700, belongs to a small protein family comprising in addition AT4G35780 and AT4G38470. All three proteins were ex...
Article
Full-text available
The import of nuclear-encoded proteins into chloroplasts is tightly controlled on both sides of the envelope membranes. Regulatory circuits include redox-control as well as calcium-regulation, with calmodulin being the likely mediator of the latter. Using affinity-chromatography on calmodulin-agarose, we could identify the inner envelope translocon...
Chapter
Chloroplasts are the characteristic organelles of photosynthetic algae and plants. They originated from a cyanobac terial ancestor that was engulfed by a eukaryotic host cell and subsequently transformed into an organelle. As a result of this heritage, chloroplasts are surrounded by a double membrane, the outer and inner envelope. Plastid proteins...
Article
Chloroplasts are specific plant organelles of prokaryotic origin. They are separated from the surrounding cell by a double membrane, which represents an effective barrier for the transport of metabolites and proteins. Specific transporters in the inner envelope membrane have been described, which facilitate the exchange of metabolites. In contrast,...
Article
The majority of chloroplast proteins is nuclear-encoded and therefore synthesized on cytosolic ribosomes. In order to enter the chloroplast, these proteins have to cross the double-membrane surrounding the organelle. This is achieved by means of two hetero-oligomeric protein complexes in the outer and inner envelope, the Toc and Tic translocon. The...