TY  - GEN
A1  - Barbosa Pfannes, Eva Katharina
A1  - Anielski, Alexander
A1  - Gerhardt, Matthias
A1  - Beta, Carsten
T1  - Intracellular photoactivation of caged cGMP induces myosin II and actin responses in motile cells
N2  - Cyclic GMP (cGMP) is a ubiquitous second messenger in eukaryotic cells. It is assumed to regulate the association of myosin II with the cytoskeleton of motile cells. When cells of the social amoeba Dictyostelium discoideum are exposed to chemoattractants or to increased osmotic stress, intracellular cGMP levels rise, preceding the accumulation of myosin II in the cell cortex. To directly investigate the impact of intracellular cGMP on cytoskeletal dynamics in a living cell, we released cGMP inside the cell by laser-induced photo-cleavage of a caged precursor. With this approach, we could directly show in a live cell experiment that an increase in intracellular cGMP indeed induces myosin II to accumulate in the cortex. Unexpectedly, we observed for the first time that also the amount of filamentous actin in the cell cortex increases upon a rise in the cGMP concentration, independently of cAMP receptor activation and signaling. We discuss our results in the light of recent work on the cGMP signaling pathway and suggest possible links between cGMP signaling and the actin system.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 239 
KW  - cyclic-gmp
KW  - dictyostelium-discoideum
KW  - ena/vasp proteins
KW  - osmotic-stress
KW  - chemotaxis
KW  - phosphorylation
KW  - amp
KW  - cytoskeleton
KW  - oscillations
KW  - chemoattractant
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-94984
SP  - 1456
EP  - 1463
ER  - 
TY  - THES
A1  - Durek, Pawel
T1  - Comparative analysis of molecular interaction networks : the interplay between spatial and functional organizing principles
T1  - Vergleichende Analyse molekularer Interaktionsnetzwerke : der Zusammenhang von räumlichen und funktionellen Organisationsprinzipien
N2  - The study of biological interaction networks is a central theme in systems biology. Here, we investigate common as well as differentiating principles of molecular interaction networks associated with different levels of molecular organization. They include metabolic pathway maps, protein-protein interaction networks as well as kinase interaction networks. First, we present an integrated analysis of metabolic pathway maps and protein-protein interaction networks (PIN). It has long been established that successive enzymatic steps are often catalyzed by physically interacting proteins forming permanent or transient multi-enzyme complexes. Inspecting high-throughput PIN data, it has been shown recently that, indeed, enzymes involved in successive reactions are generally more likely to interact than other protein pairs. In this study, we expanded this line of research to include comparisons of the respective underlying network topologies as well as to investigate whether the spatial organization of enzyme interactions correlates with metabolic efficiency. Analyzing yeast data, we detected long-range correlations between shortest paths between proteins in both network types suggesting a mutual correspondence of both network architectures. We discovered that the organizing principles of physical interactions between metabolic enzymes differ from the general PIN of all proteins. While physical interactions between proteins are generally dissortative, enzyme interactions were observed to be assortative. Thus, enzymes frequently interact with other enzymes of similar rather than different degree. Enzymes carrying high flux loads are more likely to physically interact than enzymes with lower metabolic throughput. In particular, enzymes associated with catabolic pathways as well as enzymes involved in the biosynthesis of complex molecules were found to exhibit high degrees of physical clustering. Single proteins were identified that connect major components of the cellular metabolism and hence might be essential for the structural integrity of several biosynthetic systems. Besides metabolic aspects of PINs, we investigated the characteristic topological properties of protein interactions involved in signaling and regulatory functions mediated by kinase interactions. Characteristic topological differences between PINs associated with metabolism, and those describing phosphorylation networks were revealed and shown to reflect the different modes of biological operation of both network types. The construction of phosphorylation networks is based on the identification of specific kinase-target relations including the determination of the actual phosphorylation sites (P-sites). The computational prediction of P-sites as well as the identification of involved kinases still suffers from insufficient accuracies and specificities of the underlying prediction algorithms, and the experimental identification in a genome-scale manner is not (yet) doable. Computational prediction methods have focused primarily on extracting predictive features from the local, one-dimensional sequence information surrounding P-sites. However the recognition of such motifs by the respective kinases is a spatial event. Therefore, we characterized the spatial distributions of amino acid residue types around P-sites and extracted signature 3D-profiles. We then tested the added value of spatial information on the prediction performance. When compared to sequence-only based predictors, a consistent performance gain was obtained. The availability of reliable training data of experimentally determined P-sites is critical for the development of computational prediction methods. As part of this thesis, we provide an assessment of false-positive rates of phosphoproteomic data.
N2  - Ein zentrales Thema der Systembiologie ist die Untersuchung biologischer Interaktionsnetzwerke. In der vorliegenden Arbeit wurden gemeinsame sowie differenzierende Prinzipien molekularer Interaktionsnetzwerke untersucht, die sich durch unterschiedliche Ebenen der molekulareren Organisation auszeichnen. Zu den untersuchten Interaktionsnetzwerken gehörten Netzwerke, die auf metabolischen Wechselwirkungen, physikalischen Wechselwirkungen zwischen Proteinen und Kinase-Interaktionen aufbauen. Zunächst wird eine integrativen Analyse der metabolischen Pfade und Protein Interaktionsnetzwerke vorgestellt. Es wird seit schon seit langem angenommen, dass aufeinander folgende enzymatische Schritte oft durch permanente oder transiente Multienzymkomplexe, die auf physikalischen Wechselwirkungen der involvierten Proteine basieren, katalysiert werden. Diese Annahme konnte durch die Auswertung von Ergebnissen aus Hochdurchsatz-Experimenten bestätigt werden. Demnach treten aufeinander folgende Enzyme häufiger in physikalische Wechselwirkung als zufällige Enzympaare. Die vorliegende Arbeit geht in ihrer Analyse weiter, in dem die Topologien der zugrundeliegenden Netzwerke, die auf metabolischen und physikalischen Wechselwirkungen basieren verglichen werden und der Zusammenhang zwischen der räumlichen Organisation der Enzyme und der metabolischen Effizienz gesucht wird. Ausgehend von Interaktionsdaten aus Hefe hat die Analyse der auf metabolischen und physikalischen Wechselwirkungen aufbauenden Interaktionswege eine weitgehende Korrelation der Distanzen aufgezeigt und somit eine wechselseitige Übereinstimmung der Architekturen nahegelegt. Allerdings folgen physikalische Wechselwirkungen zwischen metabolischen Enzymen anderen organisatorischen Regeln als Proteininteraktionen im allgemeinem PIN, das alle Proteininteraktionen enthält. Während Proteininteraktionen im allgemeinen PIN sich dissortativ verhalten, sind physikalische Enzyminteraktionen assortativ, d.h. dass die Anzahl der Interaktionen benachbarter Proteine im allgemeinem Netzwerk negativ und im metabolischen Netzwerk positiv korreliert. Ferner scheinen Enzyme von höherem metabolischen Durchsatz häufiger in Wechselwirkungen involviert zu sein. Enzyme der zentralen katabolischen Prozesse sowie der Biosynthese komplexer Membranlipide zeigen dabei einen besonders hohen Verknüpfungsgrad und eine dichte Clusterbildung. Einzelne Proteine wurden identifiziert, die die Hauptkomponenten des zellulären Metabolismus verbinden und so die Integrität verschiedener biosynthetischer Systeme essenziell beeinflussen könnten. Neben dem metabolischen Aspekt der PIN wurde auch der Aspekt der Regulation sowie der Signaltransduktion, der Kinase-Interaktionen, näher analysiert. Dabei wurden charakteristische topologische Unterschiede der mit dem Metabolismus und der Phosphorylierung assoziierten PIN gefunden, die die unterschiedlichen Aufgaben beider Netzwerke widerspiegeln. Die Rekonstruktion von Phosphorylierungs-Netzwerken basiert im Wesentlichen auf der Vorhersage von Kinase-Zielprotein Relationen und kann deshalb immer noch an der nicht genügenden Vorhersagegüte der angewandten Vorhersage-Algorithmen während der Bestimmung von Phosphorylierungsstellen (P-Stellen) und der dazugehörigen Kinasen leiden. Auch die experimentelle, genomweite Bestimmung der P-Stellen ist (noch) nicht durchführbar. Bisherige computergestützte Vorhersagemethoden beruhten für gewöhnlich auf der Auswertung charakteristischer Merkmale der lokalen, die P-Stelle umgebenden Proteinsequenz. Dieser Ansatz wird durch die Verwendung räumlicher 3D-Information in der vorliegenden Arbeit erweitert. Hierbei wird die Verteilung der Aminosäuren um die P-Stelle berechnet und spezifische 3D-Signaturen zur Vorhersage extrahiert. Beim Vergleich mit sequenz-basierten Vorhersagemethoden konnte eine konsistente Verbesserung der Vorhersage durch die Einbeziehung räumlicher Information gezeigt werden. Weiterhin wird in der vorliegenden Arbeit auch der Frage nach der Fehlerrate der experimentellen Phosphoprotein-Daten nachgegangen und ihre Verlässlichkeit bewertet. Die Verfügbarkeit eines verlässlichen Datensatzes ist bei der Entwicklung einer Vorhersagemethode ein entscheidendes Kriterium.
KW  - Proteinphosphorylation
KW  - Systembiologie
KW  - Netzwerke
KW  - metabolisch
KW  - phosphorylation
KW  - systemsbiology
KW  - networks
KW  - metabolic
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-31439
ER  - 
TY  - JOUR
A1  - Fichtner, Franziska
A1  - Olas, Justyna Jadwiga
A1  - Feil, Regina
A1  - Watanabe, Mutsumi
A1  - Krause, Ursula
A1  - Hoefgen, Rainer
A1  - Stitt, Mark
A1  - Lunn, John Edward
T1  - Functional features of Trehalose-6-Phosphate Synthase 1
BT  - an essential enzyme in Arabidopsis
JF  - The Plant Cell
N2  - Tre6P synthesis by TPS1 is essential for embryogenesis and postembryonic growth in Arabidopsis, and appropriate Suc signaling by Tre6P is dependent on the noncatalytic domains of TPS1. In Arabidopsis (Arabidopsis thaliana), TREHALOSE-6-PHOSPHATE SYNTHASE1 (TPS1) catalyzes the synthesis of the sucrose-signaling metabolite trehalose 6-phosphate (Tre6P) and is essential for embryogenesis and normal postembryonic growth and development. To understand its molecular functions, we transformed the embryo-lethal tps1-1 null mutant with various forms of TPS1 and with a heterologous TPS (OtsA) from Escherichia coli, under the control of the TPS1 promoter, and tested for complementation. TPS1 protein localized predominantly in the phloem-loading zone and guard cells in leaves, root vasculature, and shoot apical meristem, implicating it in both local and systemic signaling of Suc status. The protein is targeted mainly to the nucleus. Restoring Tre6P synthesis was both necessary and sufficient to rescue the tps1-1 mutant through embryogenesis. However, postembryonic growth and the sucrose-Tre6P relationship were disrupted in some complementation lines. A point mutation (A119W) in the catalytic domain or truncating the C-terminal domain of TPS1 severely compromised growth. Despite having high Tre6P levels, these plants never flowered, possibly because Tre6P signaling was disrupted by two unidentified disaccharide-monophosphates that appeared in these plants. The noncatalytic domains of TPS1 ensure its targeting to the correct subcellular compartment and its catalytic fidelity and are required for appropriate signaling of Suc status by Tre6P.
KW  - cyanobacterial sucrose-phosphatase
KW  - trehalose 6-phosphate
KW  - vegetative growth
KW  - crystal-structure
KW  - gene-expression
KW  - thaliana
KW  - metabolism
KW  - phosphorylation
KW  - reveals
KW  - proteins
Y1  - 2020
U6  - https://doi.org/10.1105/tpc.19.00837
SN  - 0032-0781
SN  - 1471-9053
VL  - 32
IS  - 6
SP  - 1949
EP  - 1972
PB  - Oxford University Press
CY  - Oxford
ER  - 
TY  - GEN
A1  - Fichtner, Franziska
A1  - Olas, Justyna Jadwiga
A1  - Feil, Regina
A1  - Watanabe, Mutsumi
A1  - Krause, Ursula
A1  - Hoefgen, Rainer
A1  - Stitt, Mark
A1  - Lunn, John Edward
T1  - Functional features of Trehalose-6-Phosphate Synthase 1
BT  - an essential enzyme in Arabidopsis
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Tre6P synthesis by TPS1 is essential for embryogenesis and postembryonic growth in Arabidopsis, and appropriate Suc signaling by Tre6P is dependent on the noncatalytic domains of TPS1. In Arabidopsis (Arabidopsis thaliana), TREHALOSE-6-PHOSPHATE SYNTHASE1 (TPS1) catalyzes the synthesis of the sucrose-signaling metabolite trehalose 6-phosphate (Tre6P) and is essential for embryogenesis and normal postembryonic growth and development. To understand its molecular functions, we transformed the embryo-lethal tps1-1 null mutant with various forms of TPS1 and with a heterologous TPS (OtsA) from Escherichia coli, under the control of the TPS1 promoter, and tested for complementation. TPS1 protein localized predominantly in the phloem-loading zone and guard cells in leaves, root vasculature, and shoot apical meristem, implicating it in both local and systemic signaling of Suc status. The protein is targeted mainly to the nucleus. Restoring Tre6P synthesis was both necessary and sufficient to rescue the tps1-1 mutant through embryogenesis. However, postembryonic growth and the sucrose-Tre6P relationship were disrupted in some complementation lines. A point mutation (A119W) in the catalytic domain or truncating the C-terminal domain of TPS1 severely compromised growth. Despite having high Tre6P levels, these plants never flowered, possibly because Tre6P signaling was disrupted by two unidentified disaccharide-monophosphates that appeared in these plants. The noncatalytic domains of TPS1 ensure its targeting to the correct subcellular compartment and its catalytic fidelity and are required for appropriate signaling of Suc status by Tre6P.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1432 
KW  - cyanobacterial sucrose-phosphatase
KW  - trehalose 6-phosphate
KW  - vegetative growth
KW  - crystal-structure
KW  - gene-expression
KW  - thaliana
KW  - metabolism
KW  - phosphorylation
KW  - reveals
KW  - proteins
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-516532
SN  - 1866-8372
IS  - 6
ER  - 
TY  - THES
A1  - Nitschke, Felix
T1  - Phosphorylation of polyglycans, especially glycogen and starch
T1  - Phosphorylierung von Polysacchariden, insbesondere bei Glykogen und Stärke
N2  - Functional metabolism of storage carbohydrates is vital to plants and animals. The water-soluble glycogen in animal cells and the amylopectin which is the major component of water-insoluble starch granules residing in plant plastids are chemically similar as they consist of α-1,6 branched α-1,4 glucan chains. Synthesis and degradation of transitory starch and of glycogen are accomplished by a set of enzymatic activities that to some extend are also similar in plants and animals. Chain elongation, branching, and debranching are achieved by synthases, branching enzymes, and debranching enzymes, respectively. Similarly, both types of polyglucans contain low amounts of phosphate esters whose abundance varies depending on species and organs. Starch is selectively phosphorylated by at least two dikinases (GWD and PWD) at the glucosyl carbons C6 and C3 and dephosphorylated by the phosphatase SEX4 and SEX4-like enzymes. In Arabidopsis insufficiency in starch phosphorylation or dephosphorylation results in largely impaired starch turnover, starch accumulation, and often in retardation of growth. In humans the progressive neurodegenerative epilepsy, Lafora disease, is the result of a defective enzyme (laforin) that is functional equivalent to the starch phosphatase SEX4 and capable of glycogen dephosphorylation. Patients lacking laforin progressively accumulate unphysiologically structured insoluble glycogen-derived particles (Lafora bodies) in many tissues including brain. Previous results concerning the carbon position of glycogen phosphate are contradictory. Currently it is believed that glycogen is esterified exclusively at the carbon positions C2 and C3 and that the monophosphate esters, being incorporated via a side reaction of glycogen synthase (GS), lack any specific function but are rather an enzymatic error that needs to be corrected. In this study a versatile and highly sensitive enzymatic cycling assay was established that enables quantification of very small G6P amounts in the presence of high concentrations of non-target compounds as present in hydrolysates of polysaccharides, such as starch, glycogen, or cytosolic heteroglycans in plants. Following validation of the G6P determination by analyzing previously characterized starches G6P was quantified in hydrolysates of various glycogen samples and in plant heteroglycans. Interestingly, glucosyl C6 phosphate is present in all glycogen preparations examined, the abundance varying between glycogens of different sources. Additionally, it was shown that carbon C6 is severely hyperphosphorylated in glycogen of Lafora disease mouse model and that laforin is capable of removing C6 phosphate from glycogen. After enrichment of phosphoglucans from amylolytically degraded glycogen, several techniques of two-dimensional NMR were applied that independently proved the existence of 6-phosphoglucosyl residues in glycogen and confirmed the recently described phosphorylation sites C2 and C3. C6 phosphate is neither Lafora disease- nor species-, or organ-specific as it was demonstrated in liver glycogen from laforin-deficient mice and in that of wild type rabbit skeletal muscle. The distribution of 6-phosphoglucosyl residues was analyzed in glycogen molecules and has been found to be uneven. Gradual degradation experiments revealed that C6 phosphate is more abundant in central parts of the glycogen molecules and in molecules possessing longer glucan chains. Glycogen of Lafora disease mice consistently contains a higher proportion of longer chains while most short chains were reduced as compared to wild type. Together with results recently published (Nitschke et al., 2013) the findings of this work completely unhinge the hypothesis of GS-mediated phosphate incorporation as the respective reaction mechanism excludes phosphorylation of this glucosyl carbon, and as it is difficult to explain an uneven distribution of C6 phosphate by a stochastic event. Indeed the results rather point to a specific function of 6-phosphoglucosyl residues in the metabolism of polysaccharides as they are present in starch, glycogen, and, as described in this study, in heteroglycans of Arabidopsis. In the latter the function of phosphate remains unclear but this study provides evidence that in starch and glycogen it is related to branching. Moreover a role of C6 phosphate in the early stages of glycogen synthesis is suggested. By rejecting the current view on glycogen phosphate to be a stochastic biochemical error the results permit a wider view on putative roles of glycogen phosphate and on alternative biochemical ways of glycogen phosphorylation which for many reasons are likely to be mediated by distinct phosphorylating enzymes as it is realized in starch metabolism of plants. Better understanding of the enzymology underlying glycogen phosphorylation implies new possibilities of Lafora disease treatment.
N2  - Pflanzen und Tiere speichern Glukose in hochmolekularen Kohlenhydraten, um diese bei Bedarf unter anderem zur Gewinnung von Energie zu nutzen. Amylopectin, der größte Bestandteil des pflanzlichen Speicherkohlenhydrats Stärke, und das tierische Äquivalent Glykogen sind chemisch betrachtet ähnlich, denn sie bestehen aus verzweigten Ketten, deren Bausteine (Glukosylreste) auf identische Weise miteinander verbunden sind. Zudem kommen in beiden Kohlenhydraten kleine aber ähnliche Mengen von Phosphatgruppen vor, die offenbar eine tragende Rolle in Pflanzen und Tieren spielen. Ist in Pflanzen der Einbau oder die Entfernung von Phosphatgruppen in bzw. aus Stärke gestört, so ist oft der gesamte Stärkestoffwechsel beeinträchtigt. Dies zeigt sich unter anderem in der übermäßigen Akkumulation von Stärke und in Wachstumsverzögerungen der gesamten Pflanze. Beim Menschen und anderen Säugern beruht eine schwere Form der Epilepsie (Lafora disease) auf einer Störung des Glykogenstoffwechsels. Sie wird durch das erblich bedingte Fehlen eines Enzyms ausgelöst, das Phosphatgruppen aus dem Glykogen entfernt. Während die Enzyme, die für die Entfernung des Phosphats aus Stärke und Glykogen verantwortlich sind, hohe Ähnlichkeit aufweisen, ist momentan die Ansicht weit verbreitet, dass der Einbau von Phosphat in beide Speicherkohlenhydrate auf höchst unterschiedliche Weise erfolgt. In Pflanzen sind zwei Enzyme bekannt, die Phosphatgruppen an unterschiedlichen Stellen in Glukosylreste einbauen (Kohlenstoffatome 6 und 3). In Tieren soll eine seltene, unvermeidbare und zufällig auftretende Nebenreaktion eines Enzyms, das eigentlich die Ketten des Glykogens verlängert (Glykogen-Synthase), den Einbau von Phosphat bewirken, der somit als unwillkürlich gilt und weithin als „biochemischer Fehler“ (mit fatalen Konsequenzen bei ausbleibender Korrektur) betrachtet wird. In den Glukosylresten des Glykogens sollen ausschließlich die C-Atome 2 und 3 phosphoryliert sein. Die Ergebnisse dieser Arbeit zeigen mittels zweier unabhängiger Methoden, dass Glykogen auch am Glukosyl-Kohlenstoff 6 phosphoryliert ist, der Phosphatposition, die in der Stärke am häufigsten vorkommt. Die Tatsache, dass in dieser Arbeit Phosphat neben Stärke auch erstmals an Glukosylresten von anderen pflanzlichen Kohlenhydraten (wasserlösliche Heteroglykane) nachgewiesen werden konnte, lässt vermuten, dass Phosphorylierung ein generelles Phänomen bei Polysacchariden ist. Des Weiteren wiesen die Ergebnisse darauf hin, dass Phosphat im Glykogen, wie auch in der Stärke, einem bestimmten Zweck dient, der im Zusammenhang mit der Regulation von Kettenverzweigung steht, und dass kein zufälliges biochemisches Ereignis für den Einbau verantwortlich sein kann. Aufgrund der grundlegenden Ähnlichkeiten im Stärke- und Glykogenstoffwechsel, liegt es nahe, dass die Phosphorylierung von Glykogen, ähnlich der von Stärke, ebenfalls durch spezifische Enzyme bewirkt wird. Ein besseres Verständnis der Mechanismen, die der Glykogen-Phosphorylierung zugrunde liegen, kann neue Möglichkeiten der Behandlung von Lafora disease aufzeigen.
KW  - Stärke
KW  - Glykogen
KW  - Phosphorylierung
KW  - NMR
KW  - Lafora disease
KW  - starch
KW  - glycogen
KW  - phosphorylation
KW  - NMR
KW  - Lafora disease
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-67396
ER  - 
TY  - GEN
A1  - Prát, Tomáš
A1  - Hajny ́, Jakub
A1  - Grunewald, Wim
A1  - Vasileva, Mina
A1  - Molnár, Gergely
A1  - Tejos, Ricardo
A1  - Schmid, Markus
A1  - Sauer, Michael
A1  - Friml, Jiří
T1  - WRKY23 is a component of the transcriptional network mediating auxin feedback on PIN polarity
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Auxin is unique among plant hormones due to its directional transport that is mediated by the polarly distributed PIN auxin transporters at the plasma membrane. The canalization hypothesis proposes that the auxin feedback on its polar flow is a crucial, plant-specific mechanism mediating multiple self-organizing developmental processes. Here, we used the auxin effect on the PIN polar localization in Arabidopsis thaliana roots as a proxy for the auxin feedback on the PIN polarity during canalization. We performed microarray experiments to find regulators of this process that act downstream of auxin. We identified genes that were transcriptionally regulated by auxin in an AXR3/IAA17-and ARF7/ARF19-dependent manner. Besides the known components of the PIN polarity, such as PID and PIP5K kinases, a number of potential new regulators were detected, among which the WRKY23 transcription factor, which was characterized in more detail. Gain-and loss-of-function mutants confirmed a role for WRKY23 in mediating the auxin effect on the PIN polarity. Accordingly, processes requiring auxin-mediated PIN polarity rearrangements, such as vascular tissue development during leaf venation, showed a higher WRKY23 expression and required the WRKY23 activity. Our results provide initial insights into the auxin transcriptional network acting upstream of PIN polarization and, potentially, canalization-mediated plant development.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1123 
KW  - apical-basal axis
KW  - arabidopsis-thaliana
KW  - root gravitropism
KW  - DNA-binding
KW  - gene-expression
KW  - transport
KW  - efflux
KW  - canalization
KW  - plants
KW  - phosphorylation
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-446331
SN  - 1866-8372
IS  - 1123
ER  - 
TY  - JOUR
A1  - Schmieder, Peter
A1  - Nitschke, Felix
A1  - Steup, Martin
A1  - Mallow, Keven
A1  - Specker, Edgar
T1  - Determination of glucan phosphorylation using heteronuclear H-1,C-13 double and H-1,C-13,P-31 triple-resonance NMR spectra
JF  - Magnetic resonance in chemistry
N2  - Phosphorylation and dephosphorylation of starch and glycogen are important for their physicochemical properties and also their physiological functions. It is therefore desirable to reliably determine the phosphorylation sites. Heteronuclear multidimensional NMR-spectroscopy is in principle a straightforward analytical approach even for complex carbohydrate molecules. With heterogeneous samples from natural sources, however, the task becomes more difficult because a full assignment of the resonances of the carbohydrates is impossible to obtain. Here, we show that the combination of heteronuclear H-1,C-13 and H-1,C-13,P-31 techniques and information derived from spectra of a set of reference compounds can lead to an unambiguous determination of the phosphorylation sites even in heterogeneous samples.
KW  - heteronuclear NMR
KW  - triple resonance
KW  - phosphorylation
KW  - starch
Y1  - 2013
U6  - https://doi.org/10.1002/mrc.3996
SN  - 0749-1581
VL  - 51
IS  - 10
SP  - 655
EP  - 661
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - GEN
A1  - Zurnic, Irena
A1  - Hütter, Sylvia
A1  - Rzeha, Ute
A1  - Stanke, Nicole
A1  - Reh, Juliane
A1  - Müllers, Erik
A1  - Hamann, Martin V.
A1  - Kern, Tobias
A1  - Gerresheim, Gesche K.
A1  - Lindel, Fabian
A1  - Serrao, Erik
A1  - Lesbats, Paul
A1  - Engelman, Alan N.
A1  - Cherepanov, Peter
A1  - Lindemann, Dirk
T1  - Interactions of prototype foamy virus capsids with host cell polo-like kinases are important for efficient viral DNA integration
T2  - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe
N2  - Unlike for other retroviruses, only a few host cell factors that aid the replication of foamy viruses (FVs) via interaction with viral structural components are known. Using a yeast-two-hybrid (Y2H) screen with prototype FV (PFV) Gag protein as bait we identified human polo-like kinase 2 (hPLK2), a member of cell cycle regulatory kinases, as a new interactor of PFV capsids. Further Y2H studies confirmed interaction of PFV Gag with several PLKs of both human and rat origin. A consensus Ser-Thr/Ser-Pro (S-T/S-P) motif in Gag, which is conserved among primate FVs and phosphorylated in PFV virions, was essential for recognition by PLKs. In the case of rat PLK2, functional kinase and polo-box domains were required for interaction with PFV Gag. Fluorescently-tagged PFV Gag, through its chromatin tethering function, selectively relocalized ectopically expressed eGFP-tagged PLK proteins to mitotic chromosomes in a Gag STP motif-dependent manner, confirming a specific and dominant nature of the Gag-PLK interaction in mammalian cells. The functional relevance of the Gag-PLK interaction was examined in the context of replication-competent FVs and single-round PFV vectors. Although STP motif mutated viruses displayed wild type (wt) particle release, RNA packaging and intra-particle reverse transcription, their replication capacity was decreased 3-fold in single-cycle infections, and up to 20-fold in spreading infections over an extended time period. Strikingly similar defects were observed when cells infected with single-round wt Gag PFV vectors were treated with a pan PLK inhibitor. Analysis of entry kinetics of the mutant viruses indicated a post-fusion defect resulting in delayed and reduced integration, which was accompanied with an enhanced preference to integrate into heterochromatin. We conclude that interaction between PFV Gag and cellular PLK proteins is important for early replication steps of PFV within host cells.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 580 
KW  - core protein
KW  - HIV-1 infection
KW  - retroviral integration
KW  - reverse transcription
KW  - nuclear-localization
KW  - box domain
KW  - in-vivo
KW  - Gag
KW  - PLK1
KW  - phosphorylation
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-411317
SN  - 1866-8372
IS  - 580
ER  -