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Publikationen - Natur- und Wirkstoffchemie

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Preprints

Osmolovskaya, N.; Shumilina, J.; Kim, A.; Didio, A.; Grishina, T.; Bilova, T.; Keltsieva, O. A.; Zhukov, V.; Tikhonovich, I.; Tarakhovskaya, E.; Wessjohann, L. A.; Frolov, A.; Methodology of Drought Stress Research: Experimental Setup and Physiological Characterization Preprints (2018) DOI: 10.20944/preprints201812.0145.v1

Drought is one of the major stress factors affecting growth and development of plants. In this context, drought-related losses of crop plant productivity impede sustainable agriculture all over the world. In general, plants responses to water deficit by multiple physiological and metabolic adaptations at the molecular, cellular and organism levels. To understand the underlying mechanisms of drought tolerance, adequate stress models and arrays of reliable stress markers are required. Therefore, in this review we comprehensively address currently available models of drought stress, based on culturing plants in soil, hydroponic or agar culture. These experimental setups give access to different aspects of plant response to drought, like decrease of tissue water potential, reduction of stomata conductance and photosynthesis efficiency, accumulation of low-molecular weight solutes (metabolic adjustment) and drought protective proteins. Till now, this pattern of markers was successfully extended to the methods of enzyme chemistry, molecular biology and omics techniques. Thus, conventional tests can be efficiently complemented by determination of phytohormone and reactive oxygen species (ROS) contents, activities of antioxidant enzymes, as well as comprehensive profiling of transcriptome, proteome and metabolome.
Preprints

Mamontova, T.; Lukasheva, E.; Mavropolo-Stolyarenko, G.; Proksch, C.; Bilova, T.; Kim, A.; Babakov, V.; Grishina, T.; Hoehenwarter, W.; Medvedev, S.; Smolikova, G.; Frolov, A.; Proteome Map of Pea (Pisum Sativum L.) Embryos Containing Different Amounts of Residual Chlorophylls Preprints (2018) DOI: 10.20944/preprints201812.0069.v1

Due to low culturing costs and high seed protein contents, legumes represent the main global source of food protein. Pea (Pisum sativum L.) is one of the major economically important legume crops, impacting both animal feed and human nutrition. Therefore, the quality of pea seeds needs to be ensured in the context of sustainable crop production and nutritional efficiency. Obviously, changes in seed protein patterns might directly affect both of these aspects. Thus, here we address the pea seed proteome in more detail and provide, to the best of our knowledge, the most comprehensive annotation of the functions and intracellular localization of pea seed proteins. Accordingly, 1938 and 1989 non-redundant proteins were identified in yellow and green pea seeds, in total. Only 35 and 44 proteins, respectively, could be additionally identified after protamine sulfate precipitation (PSP) potentially indicating the high efficiency of our experimental workflow. In total 981 protein groups could be assigned to 34 functional classes, which were to a large extent differentially represented in yellow and green seeds. Closer analysis of these differences by processing of the data in KEGG and String databases revealed their possible relation to a higher metabolic status and reduced longevity of green seeds.
Publikation

Wang, D.; Pentzold, S.; Kunert, M.; Groth, M.; Brandt, W.; Pasteels, J. M.; Boland, W.; Burse, A.; A subset of chemosensory genes differs between two populations of a specialized leaf beetle after host plant shift Ecol. Evol. 8, 8055-8075, (2018) DOI: 10.1002/ece3.4246

Due to its fundamental role in shaping host selection behavior, we have analyzed the chemosensory repertoire of Chrysomela lapponica. This specialized leaf beetle evolved distinct populations which shifted from the ancestral host plant, willow (Salix sp., Salicaceae), to birch (Betula rotundifolia, Betulaceae). We identified 114 chemosensory candidate genes in adult C. lapponica: 41 olfactory receptors (ORs), eight gustatory receptors, 17 ionotropic receptors, four sensory neuron membrane proteins, 32 odorant binding proteins (OBPs), and 12 chemosensory proteins (CSP) by RNA‐seq. Differential expression analyses in the antennae revealed significant upregulation of one minus‐C OBP (ClapOBP27) and one CSP (ClapCSP12) in the willow feeders. In contrast, one OR (ClapOR17), four minus‐C OBPs (ClapOBP02, 07, 13, 20), and one plus‐C OBP (ClapOBP32) were significantly upregulated in birch feeders. The differential expression pattern in the legs was more complex. To narrow down putative ligands acting as cues for host discrimination, the relative abundance and diversity of volatiles of the two host plant species were analyzed. In addition to salicylaldehyde (willow‐specific), both plant species differed mainly in their emission rate of terpenoids such as (E,E)‐α‐farnesene (high in willow) or 4,8‐dimethylnona‐1,3,7‐triene (high in birch). Qualitatively, the volatiles were similar between willow and birch leaves constituting an “olfactory bridge” for the beetles. Subsequent structural modeling of the three most differentially expressed OBPs and docking studies using 22 host volatiles indicated that ligands bind with varying affinity. We suggest that the evolution of particularly minus‐C OBPs and ORs in C. lapponica facilitated its host plant shift via chemosensation of the phytochemicals from birch as novel host plant.
Publikation

Walther, T.; Herzog, R.; Kaluđerović, M. R.; Wagner, C.; Schmidt, H.; Kaluđerović, G. N.; Traceable platinum(II) complexes with alkylene diamine-derived ligands: synthesis, characterization and in vitro studies J. Coord. Chem. 71, 243-257, (2018) DOI: 10.1080/00958972.2018.1431392

Diiodido- (6a/6b) and dichloridoplatinum(II) complexes (7a/7b) with fluorescent ligands 2-[(2-aminoethyl)amino]ethyl-2-(methylamino)benzoate (5a) and 2-amino-1-(aminoethyl)ethyl-2-(methylamino)benzoate (5b) were prepared and characterized by elemental analysis, ESI-MS analysis, fluorescence spectrometry, as well as 1H, 13C, and 195Pt NMR spectroscopy. All compounds have been tested against A2780 ovarian cancer, A549 lung carcinoma, and HT-29 colon cancer cell lines using sulforhodamine-B assay. The activity increased from ligand precursors, diiodido- to dichloridoplatinum(II) complexes, except against HT-29 cell line where diiodido and dichlorido expressed similar activity. These compounds enter the tumor cells and emit a bright fluorescence at ca. 470 nm, mainly targeting nuclei.
Publikation

Vattekkatte, A.; Garms, S.; Brandt, W.; Boland, W.; Enhanced structural diversity in terpenoid biosynthesis: enzymes, substrates and cofactors Org. Biomol. Chem. 16, 348-362, (2018) DOI: 10.1039/C7OB02040F

The enormous diversity of terpenes found in nature is generated by enzymes known as terpene synthases, or cyclases. Some are also known for their ability to convert a single substrate into multiple products. This review comprises monoterpene and sesquiterpene synthases that are multiproduct in nature along with the regulation factors that can alter the product specificity of multiproduct terpene synthases without genetic mutations. Variations in specific assay conditions with focus on shifts in product specificity based on change in metal cofactors, assay pH and substrate geometry are described. Alterations in these simple cellular conditions provide the organism with enhanced chemodiversity without investing into new enzymatic architecture. This versatility to modulate product diversity grants organisms, especially immobile ones like plants with access to an enhanced defensive repertoire by simply altering cofactors, pH level and substrate geometry.
Publikation

Tessema, E. N.; Gebre-Mariam, T.; Frolov, A.; Wohlrab, J.; Neubert, R. H. H.; Development and validation of LC/APCI-MS method for the quantification of oat ceramides in skin permeation studies Anal. Bioanal. Chem. 410, 4775-4785, (2018) DOI: 10.1007/s00216-018-1162-z

Ceramides (CERs) are the backbone of the intercellular lipid lamellae of the stratum corneum (SC), the outer layer of the skin. Skin diseases such as atopic dermatitis, psoriasis, and aged skin are characterized by dysfunctional skin barrier and dryness which are associated with reduced levels of CERs. Replenishing the depleted epidermal CERs with exogenous CERs has been shown to have beneficial effects in improving the skin barrier and hydration. The exogenous CERs such as phyto-derived CERs (PhytoCERs) can be delivered deep into the SC using novel topical formulations. This, however, requires investigating the rate and extent of skin permeation of CERs. In this study, an LC/APCI-MS method to detect and quantify PhytoCERs in different layers of the skin has been developed and validated. The method was used to investigate the skin permeation of PhytoCERs using Franz diffusion cells after applying an amphiphilic cream containing PhytoCERs to the surface of ex vivo human skin. As plant-specific CERs are not commercially available, well-characterized CERs isolated from oat (Avena abyssinica) were used as reference standards for the development and validation of the method. The method was linear over the range of 30–1050 ng/mL and sensitive with limit of detection and quantification of 10 and 30 ng/mL, respectively. The method was also selective, accurate, and precise with minimal matrix effect (with mean matrix factor around 100%). Even if more than 85% of oat CERs in the cream remained in the cream after the incubation periods of 30, 100, and 300 min, it was possible to quantify the small quantities of oat CERs distributed across the SC, epidermis, and dermis of the skin indicating the method’s sensitivity. Therefore, the method can be used to investigate the skin permeation of oat CERs from the various pharmaceutical and cosmeceutical products without any interference from the skin constituents such as the epidermal lipids.
Publikation

Tahara, K.; Nishiguchi, M.; Frolov, A.; Mittasch, J.; Milkowski, C.; Identification of UDP glucosyltransferases from the aluminum-resistant tree Eucalyptus camaldulensis forming β-glucogallin, the precursor of hydrolyzable tannins Phytochemistry 152, 154-161, (2018) DOI: 10.1016/j.phytochem.2018.05.005

In the highly aluminum-resistant tree Eucalyptus camaldulensis, hydrolyzable tannins are proposed to play a role in internal detoxification of aluminum, which is a major factor inhibiting plant growth on acid soils. To understand and modulate the molecular mechanisms of aluminum detoxification by hydrolyzable tannins, the biosynthetic genes need to be identified. In this study, we identified and characterized genes encoding UDP-glucose:gallate glucosyltransferase, which catalyzes the formation of 1-O-galloyl-β-d-glucose (β-glucogallin), the precursor of hydrolyzable tannins. By homology-based cloning, seven full-length candidate cDNAs were isolated from E. camaldulensis and expressed in Escherichia coli as recombinant N-terminal His-tagged proteins. Phylogenetic analysis classified four of these as UDP glycosyltransferase (UGT) 84A subfamily proteins (UGT84A25a, -b, UGT84A26a, -b) and the other three as UGT84J subfamily proteins (UGT84J3, -4, -5). In vitro enzyme assays showed that the UGT84A proteins catalyzed esterification of UDP–glucose and gallic acid to form 1-O-galloyl-β-d-glucose, whereas the UGT84J proteins were inactive. Further analyses with UGT84A25a and −26a indicated that they also formed 1-O-glucose esters of other structurally related hydroxybenzoic and hydroxycinnamic acids with a preference for hydroxybenzoic acids. The UGT84A genes were expressed in leaves, stems, and roots of E. camaldulensis, regardless of aluminum stress. Taken together, our results suggest that the UGT84A subfamily enzymes of E. camaldulensis are responsible for constitutive production of 1-O-galloyl-β-d-glucose, which is the first step of hydrolyzable tannin biosynthesis.
Publikation

Storck, S. E.; Hartz, A. M.; Bernard, J.; Wolf, A.; Kachlmeier, A.; Mahringer, A.; Weggen, S.; Pahnke, J.; Pietrzik, C. U.; The concerted amyloid-beta clearance of LRP1 and ABCB1/P-gp across the blood-brain barrier is linked by PICALM Brain Behav. Immun. 73, 21-33, (2018) DOI: 10.1016/j.bbi.2018.07.017

The accumulation of neurotoxic amyloid-beta (Aβ) in the brain is a characteristic hallmark of Alzheimer’s disease (AD). The blood-brain barrier (BBB) provides a large surface area and has been shown to be an important mediator for removal of brain Aβ. Both, the ABC transporter P-glycoprotein (ABCB1/P-gp) and the receptor low-density lipoprotein receptor-related protein 1 (LRP1) have been implicated to play crucial roles in Aβ efflux from brain. Here, with immunoprecipitation experiments, co-immunostainings and dual inhibition of ABCB1/P-gp and LRP1, we show that both proteins are functionally linked, mediating a concerted transcytosis of Aβ through endothelial cells. Late-onset AD risk factor Phosphatidylinositol binding clathrin assembly protein (PICALM) is associated with both ABCB1/P-gp and LRP1 representing a functional link and guiding both proteins through the brain endothelium. Together, our results give more mechanistic insight on Aβ transport across the BBB and show that the functional interplay of different clearance proteins is needed for the rapid removal of Aβ from the brain.
Publikation

Smolikova, G.; Kreslavski, V.; Shiroglazova, O.; Bilova, T.; Sharova, E.; Frolov, A.; Medvedev, S.; Photochemical activity changes accompanying the embryogenesis of pea (Pisum sativum) with yellow and green cotyledons Funct. Plant Biol. 45, 228-235, (2018) DOI: 10.1071/FP16379

The pea seeds are photosynthetically active until the end of the maturation phase, when the embryonic chlorophylls degrade. However, in some cultivars, the underlying mechanisms are compromised, and the mature seeds preserve green colour. The residual chlorophylls can enhance oxidative degradation of reserve biomolecules, and affect thereby the quality, shelf life and nutritive value of seeds. Despite this, the formation, degradation, and physical properties of the seed chlorophylls are still not completely characterised. So here we address the dynamics of seed photochemical activity in the yellow- and green-seeded pea cultivars by the pulse amplitude modulation (PAM) fluorometric analysis. The experiments revealed the maximal photochemical activity at the early- and mid-cotyledon stages. Thereby, the active centres of PSII were saturated at the light intensity of 15–20 µmol photons m–2 s–1. Despite of their shielding from the light by the pod wall and seed coat, photochemical reactions can be registered in the seeds with green embryo. Importantly, even at the low light intensities, the photochemical activity in the coats and cotyledons could be detected. The fast transients of the chlorophyll a fluorescence revealed a higher photochemical activity in the coat of yellow-seeded cultivars in comparison to those with the green-seeded ones. However, it declined rapidly in all seeds at the late cotyledon stage, and was accompanied with the decrease of the seed water content. Thus, the termination of photosynthetic activity in seeds is triggered by their dehydration.
Publikation

Schüler, J.-A.; Neumann, S.; Müller-Hannemann, M.; Brandt, W.; ChemFrag: Chemically meaningful annotation of fragment ion mass spectra J. Mass Spectrom. 53, 1104-1115, (2018) DOI: 10.1002/jms.4278

Identification and structural determination of small molecules by mass spectrometry is an important step in chemistry and biochemistry. However, the chemically realistic annotation of a fragment ion spectrum can be a difficult challenge. We developed ChemFrag, for the detection of fragmentation pathways and the annotation of fragment ions with chemically reasonable structures. ChemFrag combines a quantum chemical with a rule‐based approach. For different doping substances as test instances, ChemFrag correctly annotates fragment ions. In most cases, the predicted fragments are chemically more realistic than those from purely combinatorial approaches, or approaches based on machine learning. The annotation generated by ChemFrag often coincides with spectra that have been manually annotated by experts. This is a major advance in peak annotation and allows a more precise automatic interpretation of mass spectra.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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