Publications
El Amerany, F.; Meddich, A.; Wahbi, S.; Porzel, A.; Taourirte, M.; Rhazi, M.; Hause, B. Foliar Application of Chitosan Increases Tomato
Growth and Influences Mycorrhization and Expression of
Endochitinase-Encoding Genes Int J Mol Sci 21, 535, (2020) DOI: 10.3390/ijms21020535
Nowadays, applying bio-organic fertilizer
(e.g., chitosan, Ch) or integrating beneficial microorganisms (e.g.,
arbuscular mycorrhizal fungi, AMF) are among the successful strategies
to promote plant growth. Here, the effect of two application modes of Ch
(foliar spray or root treatment) and Ch-derived nanoparticles (NPs) on
tomato plants colonized with the AMF Rhizophagus irregularis were
analyzed, thereby focusing on plant biomass, flowering and
mycorrhization. An increase of shoot biomass and flower number was
observed in arbuscular mycorrhizal (AM) plants sprayed with Ch. The
interaction with AMF, however, was reduced as shown by decreased
mycorrhization rates and AM-specific gene expression. To get insights
into Ch effect on mycorrhization, levels of sugars, jasmonates, abscisic
acid, and the expression of two chitinase-encoding genes were
determined in mycorrhizal roots. Ch had no effect on sugar and
phytohormone levels, but the reduced mycorrhization was correlated with
down- and upregulated expression of Chi3 and Chi9, respectively. In
contrast, application of NPs to leaves and Ch applied to the soil did
not show any effect, neither on mycorrhization rate nor on growth of
mycorrhizal plants. Concluding, Ch application to leaves enhanced plant
growth and flowering and reduced interaction with AMF, whereas root
treatment did not affect these parameters.
Publications
Leonova, T.; Popova, V.; Tsarev, A.; Henning, C.; Antonova, K.; Rogovskaya, N.; Vikhnina, M.; Baldensperger, T.; Soboleva, A.; Dinastia, E.; Dorn, M.; Shiroglasova, O.; Grishina, T.; Balcke, G. U.; Ihling, C.; Smolikova, G.; Medvedev, S.; Zhukov, V. A.; Babakov, V.; Tikhonovich, I. A.; Glomb, M. A.; Bilova, T.; Frolov, A. Does Protein Glycation Impact on the
Drought-Related Changes in Metabolism and Nutritional Properties of
Mature Pea (Pisum sativum L.) Seeds? Int J Mol Sci 21, 567, (2020) DOI: 10.3390/ijms21020567
Protein glycation is usually referred to as an array of non-enzymatic
post-translational modifications formed by reducing sugars and carbonyl
products of their degradation. The resulting advanced glycation end
products (AGEs) represent a heterogeneous group of covalent adducts,
known for their pro-inflammatory effects in mammals, and impacting on
pathogenesis of metabolic diseases and ageing. In plants, AGEs are the
markers of tissue ageing and response to environmental stressors, the
most prominent of which is drought. Although water deficit enhances
protein glycation in leaves, its effect on seed glycation profiles is
still unknown. Moreover, the effect of drought on biological activities
of seed protein in mammalian systems is still unstudied with respect to
glycation. Therefore, here we address the effects of a short-term
drought on the patterns of seed protein-bound AGEs and accompanying
alterations in pro-inflammatory properties of seed protein in the
context of seed metabolome dynamics. A short-term drought, simulated as
polyethylene glycol-induced osmotic stress and applied at the stage of
seed filling, resulted in the dramatic suppression of primary seed
metabolism, although the secondary metabolome was minimally affected.
This was accompanied with significant suppression of NF-kB activation in
human SH-SY5Y neuroblastoma cells after a treatment with protein
hydrolyzates, isolated from the mature seeds of drought-treated plants.
This effect could not be attributed to formation of known AGEs. Most
likely, the prospective anti-inflammatory effect of short-term drought
is related to antioxidant effect of unknown secondary metabolite protein
adducts, or down-regulation of unknown plant-specific AGEs due to
suppression of energy metabolism during seed filling.
Publications
Böhme, B.; Moritz, B.; Wendler, J.; Hertel, T. C.; Ihling, C.; Brandt, W.; Pietzsch, M. Enzymatic activity and thermoresistance of improved microbial transglutaminase variants Amino Acids 52, 313-326, (2020) DOI: 10.1007/s00726-019-02764-9
Microbial transglutaminase (MTG, EC 2.3.2.13)
of Streptomyces mobaraensis is widely used in industry for its ability
to synthesize isopeptide bonds between the proteinogenic side chains of
glutamine and lysine. The activated wild-type enzyme irreversibly
denatures at 60 °C with a pseudo-first-order kinetics and a half-life
time (t1/2) of 2 min. To increase the thermoresistance of MTG for higher
temperature applications, we generated 31 variants based on previous
results obtained by random mutagenesis, DNA shuffling and saturation
mutagenesis. The best variant TG16 with a specific combination of five
of seven substitutions (S2P, S23Y, S24 N, H289Y, K294L) shows a 19-fold
increased half-life at 60 °C (t1/2 = 38 min). As measured by
differential scanning fluorimetry, the transition point of thermal
unfolding was increased by 7.9 °C. Also for the thermoresistant
variants, it was shown that inactivation process follows a
pseudo-first-order reaction which is accompanied by irreversible
aggregation and intramolecular self-crosslinking of the enzyme. Although
the mutations are mostly located on the surface of the enzyme, kinetic
constants determined with the standard substrate CBZ-Gln-Gly-OH revealed
a decrease in KM from 8.6 mM (± 0.1) to 3.5 mM (± 0.1) for the
recombinant wild-type MTG and TG16, respectively. The improved
performance of TG16 at higher temperatures is exemplary demonstrated
with the crosslinking of the substrate protein β-casein at 60 °C. Using
molecular dynamics simulations, it was shown that the increased
thermoresistance is caused by a higher backbone rigidity as well as
increased hydrophobic interactions and newly formed hydrogen bridges.
Publications
Guerra, T.; Schilling, S.; Hake, K.; Gorzolka, K.; Sylvester, F.-P.; Conrads, B.; Westermann, B.; Romeis, T. Calcium‐dependent protein kinase 5 links
calcium‐signaling with N‐Hydroxy‐L‐pipecolic acid‐ and SARD1‐dependent
immune memory in systemic acquired resistance New Phytol 225, 310-325, (2020) DOI: 10.1111/nph.16147
Systemic acquired resistance (SAR) prepares
infected plants for faster and stronger defense activation upon
subsequent attacks. SAR requires an information relay from primary
infection to distal tissue and the initiation and maintenance of a
self‐maintaining phytohormone salicylic acid (SA)‐defense loop.In
spatial and temporal resolution, we show that calcium‐dependent protein
kinase CPK5 contributes to immunity and SAR. In local basal resistance,
CPK5 functions upstream of SA synthesis, perception, and signaling. In
systemic tissue, CPK5 signaling leads to accumulation of SAR‐inducing
metabolite N‐hydroxy‐L‐pipecolic acid (NHP) and SAR marker genes,
including Systemic Acquired Resistance Deficient 1 (SARD1)Plants of
increased CPK5, but not CPK6, signaling display an ‘enhanced SAR’
phenotype towards a secondary bacterial infection. In the sard1‐1
background, CPK5‐mediated basal resistance is still mounted, but NHP
concentration is reduced and enhanced SAR is lost.The biochemical
analysis estimated CPK5 half maximal kinase activity for calcium, K50
[Ca2+], to be c. 100 nM, close to the cytoplasmic resting level. This
low threshold uniquely qualifies CPK5 to decode subtle changes in
calcium, a prerequisite to signal relay and onset and maintenance of
priming at later time points in distal tissue. Our data explain why CPK5
functions as a hub in basal and systemic plant immunity.
Publications
Laub, A.; Sendatzki, A.-K.; Palfner, G.; Wessjohann, L. A.; Schmidt, J.; Arnold, N. HPTLC-DESI-HRMS-Based Profiling of Anthraquinones
in Complex Mixtures—A Proof-of-Concept Study Using Crude Extracts of
Chilean Mushrooms Foods 9, 156, (2020) DOI: 10.3390/foods9020156
High-performance thin-layer chromatography
(HPTLC) coupled with negative ion desorption electrospray ionization
high-resolution mass spectrometry (DESI-HRMS) was used for the analysis
of anthraquinones in complex crude extracts of Chilean dermocyboid
Cortinarii. For this proof-of-concept study, the known anthraquinones
emodin, physcion, endocrocin, dermolutein, hypericin, and skyrin were
identified by their elemental composition. HRMS also allowed the
differentiation of the investigated anthraquinones from accompanying
compounds with the same nominal mass in the crude extracts. An
investigation of the characteristic fragmentation pattern of skyrin in
comparison with a reference compound showed, exemplarily, the
feasibility of the method for the determination of these coloring,
bioactive and chemotaxonomically important marker compounds.
Accordingly, we demonstrate that the coupling of HPTLC with DESI-HRMS
represents an advanced and efficient technique for the detection of
anthraquinones in complex matrices. This analytical approach may be
applied in the field of anthraquinone-containing food and plants such as
Rheum spp. (rhubarb), Aloe spp., Morinda spp., Cassia spp. and others.
Furthermore, the described method can be suitable for the analysis of
anthraquinone-based colorants and dyes, which are used in the food,
cosmetic, and pharmaceutical industry.
Publications
Farag, M. A.; Abdelwareth, A.; Sallam, I. E.; el Shorbagi, M.; Jehmlich, N.; Fritz-Wallace, K.; Serena Schäpe, S.; Rolle-Kampczyk, U.; Ehrlich, A.; Wessjohann, L. A.; von Bergen, M. Metabolomics reveals impact of seven functional foods on metabolic pathways in a gut microbiota model J Adv Res 23, 47-59, (2020) DOI: 10.1016/j.jare.2020.01.001
Functional food defined as dietary supplements
that in addition to their nutritional values, can beneficially modulate
body functions becomes more and more popular but the reaction of the
intestinal microbiota to it is largely unknown. In order to analyse the
impact of functional food on the microbiota itself it is necessary to
focus on the physiology of the microbiota, which can be assessed in a
whole by untargeted metabolomics. Obtaining a detailed description of
the gut microbiota reaction to food ingredients can be a key to
understand how these organisms regulate and bioprocess many of these
food components. Extracts prepared from seven chief functional foods,
namely green tea, black tea, Opuntia ficus-indica (prickly pear, cactus
pear), black coffee, green coffee, pomegranate, and sumac were
administered to a gut consortium culture encompassing 8 microbes which
are resembling, to a large extent, the metabolic activities found in the
human gut. Samples were harvested at 0.5 and 24 h post addition of
functional food extract and from blank culture in parallel and analysed
for its metabolites composition using gas chromatography coupled to mass
spectrometry detection (GC-MS). A total of 131 metabolites were
identified belonging to organic acids, alcohols, amino acids, fatty
acids, inorganic compounds, nitrogenous compounds, nucleic acids,
phenolics, steroids and sugars, with amino acids as the most abundant
class in cultures. Considering the complexity of such datasets,
multivariate data analyses were employed to classify samples and
investigate how functional foods influence gut microbiota metabolisms.
Results from this study provided a first insights regarding how
functional foods alter gut metabolism through either induction or
inhibition of certain metabolic pathways, i.e. GABA production in the
presence of higher acidity induced by functional food metabolites such
as polyphenols. Likewise, functional food metabolites i.e., purine
alkaloids acted themselves as direct substrate in microbiota metabolism.
Publications
Abbas, G.; Haq, Q. M. I.; Hamaed, A.; Al-Sibani, M.; Hussain, H. Glucagon and Glucagon-like Peptide-1 Receptors: Promising Therapeutic Targets for an Effective Management of Diabetes Mellitus Curr Pharm Des 26, 501-508, (2020) DOI: 10.2174/1381612826666200131143231
G-protein-coupled receptors (GPCRs) are membrane-bound proteins which
are responsible for the detection of extracellular stimuli and the
origination of intracellular responses. Both glucagon and glucagon-like
peptide-1 (GLP-1) receptors belong to G protein-coupled receptor (GPCR)
superfamily. Along with insulin, glucagon and GLP-1 are critical
hormones for maintaining normal serum glucose within human body.
Glucagon generally plays its role in the liver through cyclic adenosine
monophosphate (cAMP), where it compensates the action of insulin. GLP-1
is secreted by the L-cells of the small intestine to stimulate insulin
secretion and inhibit glucagon action. Despite the extensive research
efforts and the multiple approaches adopted, the glycemic control in the
case of type-2 diabetes mellitus remains a major challenge. Therefore, a
deep understanding of the structure-function relationship of these
receptors will have great implications on future therapies in order to
maintain a normal glucose level for an extended period of time. The
antagonists of glucagon receptor that can effectively block the hepatic
glucose production, as a result of glucagon action, are highly desirable
for the tuning of the hyperglycemic state in type 2 diabetes mellitus.
In the same manner, GLP-1R agonists act as important treatment
modalities thanks to their multiple anti-diabetic actions to attain
normal glucose level. In this review article, the structural diversity
of glucagon and GLP-1 receptors along with their signaling pathways,
site-directed mutations and significance in drug discovery against
type-2 diabetes will be illustrated. Moreover, the promising non-peptide
antagonists of glucagon receptor and agonists of GLP-1 receptor, for
the management of diabetes will be presented with elaboration on the
structure-activity relationship (SAR).
Publications
Vasco, A. V.; Brode, M.; Méndez, Y.; Valdés, O.; Rivera, D. G.; Wessjohann, L. A. Synthesis of Lactam-Bridged and Lipidated Cyclo-Peptides as Promising Anti-Phytopathogenic Agents Molecules 25, 811, (2020) DOI: 10.3390/molecules25040811
Antimicrobial resistance to conventional
antibiotics and the limited alternatives to combat plant-threatening
pathogens are worldwide problems. Antibiotic lipopeptides exert
remarkable membrane activity, which usually is not prone to fast
resistance formation, and often show organism-type selectivity.
Additional modes of action commonly complement the bioactivity profiles
of such compounds. The present work describes a multicomponent-based
methodology for the synthesis of cyclic polycationic lipopeptides with
stabilized helical structures. The protocol comprises an on solid
support Ugi-4-component macrocyclization in the presence of a lipidic
isocyanide. Circular dichroism was employed to study the influence of
both macrocyclization and lipidation on the amphiphilic helical
structure in water and micellar media. First bioactivity studies against
model phytopathogens demonstrated a positive effect of the lipidation
on the antimicrobial activity.
Publications
Ricardo, M. G.; Moya, C. G.; Pérez, C. S.; Porzel, A.; Wessjohann, L. A.; Rivera, D. G. Improved Stability and Tunable Functionalization of Parallel β-Sheets via Multicomponent N-Alkylation of the Turn Moiety Angew Chem Int Ed 59, 259-263, (2020) DOI: 10.1002/anie.201912095
In contrast to the myriad of methods available
to produce α‐helices and antiparallel β‐sheets in synthetic peptides,
just a few are known for the construction of stable, non‐cyclic parallel
β‐sheets. Herein, we report an efficient on‐resin approach for the
assembly of parallel β‐sheet peptides in which the N‐alkylated turn
moiety enhances the stability and gives access to a variety of
functionalizations without modifying the parallel strands. The key
synthetic step of this strategy is the multicomponent construction of an
N‐alkylated turn using the Ugi reaction on varied isocyano‐resins. This
four‐component process assembles the orthogonally protected turn
fragment and incorporates handles serving for labeling/conjugation
purposes or for reducing peptide aggregation. NMR and circular dichroism
analyses confirm the better‐structured and more stable parallel
β‐sheets in the N‐alkylated peptides compared to the non‐functionalized
variants.
Publications
Ricardo, M. G.; Moya, C. G.; Pérez, C. S.; Porzel, A.; Wessjohann, L. A.; Rivera, D. G. Improved Stability and Tunable Functionalization of Parallel β‐Sheets via Multicomponent N‐Alkylation of the Turn Moiety Angew Chem 132, 265-269, (2020) DOI: 10.1002/ange.201912095
In contrast to the myriad of methods available
to produce α‐helices and antiparallel β‐sheets in synthetic peptides,
just a few are known for the construction of stable, non‐cyclic parallel
β‐sheets. Herein, we report an efficient on‐resin approach for the
assembly of parallel β‐sheet peptides in which the N‐alkylated turn
moiety enhances the stability and gives access to a variety of
functionalizations without modifying the parallel strands. The key
synthetic step of this strategy is the multicomponent construction of an
N‐alkylated turn using the Ugi reaction on varied isocyano‐resins. This
four‐component process assembles the orthogonally protected turn
fragment and incorporates handles serving for labeling/conjugation
purposes or for reducing peptide aggregation. NMR and circular dichroism
analyses confirm the better‐structured and more stable parallel
β‐sheets in the N‐alkylated peptides compared to the non‐functionalized
variants.