Biology subjects

Peikert, K.

Publications and source records attributed to Peikert, K..

4 recordsLinked to original sources

bioRxiv2025

In vivo activation of the dia BGC allows consolidation of the biosynthetic pathways of diaporthin, dichlorodiaporthin, diaporthinic acid, and diaporthinol

Fungal secondary metabolites exhibit remarkable chemical diversity and biological activity, making them valuable sources of bioactive compounds. A group of polyketides, with a similar core structure, have been isolated previously from different fungi - the phytotoxins diaporthin and orthosporin, the mediocre antimicrobial dichlorodiaporthin, as well as diaporthinol and diaporthinic acid. Previous studies in Aspergillus oryzae suggest that diaporthin and orthosporin originate from a different biosynthetic gene cluster than dichlorodiaporthin, while the biosynthetic routes for diaporthinic acid and diaporthinol have not yet been identified. In this study, we successfully activated the dia biosynthetic gene cluster in Trichoderma reesei via transcription factor overexpression, leading to the identification of diaporthinic acid as the primary metabolite. Structural elucidation using NMR confirmed its identity, while bioactivity assays revealed no significant antimicrobial effects. Further, diaporthin, orthosporin, dichlorodiaporthin, and diaporthinol, as well as an isomer of alternariol were attributed to the same cluster. Gene deletion experiments demonstrated that Dia1, Dia4, and Dia5 are essential for diaporthinic acid biosynthesis, with Dia4 likely catalyzing the oxidation of dichlorodiaporthin yielding diaporthinic acid. Dia2 and Dia3 were found to be dispensable, challenging previous in vitro findings for the biosynthesis of dichlorodiaporthin. These findings provide new insights into the biosynthetic network of the dia BGC, expanding our understanding of natural product biosynthesis in filamentous fungi.

biochemistry↗

bioRxiv2024

RIG-I mediated neuron-specific IFN type 1 signaling in FUS-ALS induces neurodegeneration and offers new biomarker-driven individualized treatment options for (FUS-)ALS

Recent research has demonstrated significant aberrant activation of the innate immune system in ALS model systems due to mutations in SOD1, TARDBP and C9orf72 through stimulation of the TBK1-IRF3 pathway. This pathway can be activated, for example, by cGAS-STING-dependent sensing of cytosolic DNA that accumulates as a result of chronic DNA damage and defective mitochondria, both of which have been identified as early pathology in FUS-ALS spinal motor neurons (sMNs). Therefore, we analysed innate immune pathways in isogenic and non-isogenic FUSmut iPSC-derived sMNs, which revealed upregulation of interferon-stimulated genes (ISGs) and activation of the TBK1-IRF3 pathway in FUSmut sMNs. Notably, we found evidence for accumulation of cytosolic dsRNA and its sensor RIG-I in FUS-ALS. RIG-I, but not MDA5, was found to be significantly upregulated in FUSmut sMNs, and siRNA-mediated knockdown abolished the increased IFN1 activation in FUSmut sMNs. In post-mortem analysis, RIG-I was highly expressed in the remaining -MNs. IFN treatment of FUSwt sMNs phenocopied the axonal degeneration of FUSmut sMNs. Mechanistically, DNA damage induction did not increase ISG expression, but dsRNA was increased in the mitochondria of FUSmut sMNs. Mitochondrial transcription, a known source of dsRNA, was found to be upregulated in compartmental axonal RNAseq analysis and its inhibition reduced ISGs in FUS-ALS sMNs. Furthermore, the JAK-STAT inhibitor ruxolitinib alleviated the upregulated ISG expression and reversed the axonal degeneration of sMNs. Finally, we analysed ISG expression in peripheral blood samples from 18 FUS-ALS patients, eight of whom had a significantly elevated interferon signature. Blood ISGs correlated with disease progression rate and negatively with disease duration. RIG-I-mediated innate immune activation in sMNs may be an interesting novel individualised biomarker-driven therapeutic target in (FUS-) ALS. A one-sentence summary of your paperRIG-I-I-mediated innate immune activation is found in FUS-ALS spinal motor neurons caused by cytosolic dsRNA accumulation due to mitochondrial transcriptional activation and is amenable to JAK-STAT inhibition and might thus be an interesting novel individualized biomarker-driven therapeutic approach in (FUS-) ALS

neuroscience↗

bioRxiv2024

Discovery of a novel antifungal compound, ilicicolin K, through genetic activation of the ilicicolin biosynthetic pathway in Trichoderma reesei

In the quest to discover novel antifungal agents and new antifungal production processes, we investigated the biosynthetic gene cluster (BGC) for ilicicolin H in the fungus Trichoderma reesei. While the BGC is silent under standard cultivation conditions, we achieved to activate it by over-expressing its transcription factor TriliR. Successful BGC activation was confirmed by RT-qPCR, proteomic and metabolomic analyses. Metabolomic profiling upon BGC expression revealed high-yield production of the supposed main product ilicicolin H. To elucidate the functionality of this BGC, we employed a combination of overexpression and deletions of individual biosynthetic gene cluster constituents. Deletion of triliA, encoding for the core polyketide synthase TriliA, completely ceased product formation, as expected. In contrast to previous heterologous expression experiments, we could demonstrate that the epimerase TriliE is necessary for the formation of ilicicolin H in the native host. While we hardly observed any of the previously reported side- or shunt products associated with heterologous ilicicolin H expression, we discovered a novel member of the ilicicolin family using a metabolomic molecular networking approach. This new compound, which we termed ilicicolin K, is expressed in substantial amounts in the genetically engineered Trichoderma reesei, enabling us to elucidate its structure by NMR. The structure of ilicicolin K is similar to that of ilicicolin H but differs by an additional hydroxylation and an intramolecular etherification of the hydroxyl group at the pyridone towards the tyrosine moiety of the molecule. Initial tests of ilicicolin K showed antifungal activity against Saccharomyces cerevisiae and Aspergillus nidulans with a similar minimum inhibitory concentration as ilicicolin H.

biochemistry↗

bioRxiv2021

Changes in blood cell deformability in Chorea-Acanthocytosis and effects of treatment with dasatinib or lithium

Misshaped red blood cells (RBCs), characterized by thorn-like protrusions known as acanthocytes, are a key diagnostic feature in Chorea-Acanthocytosis (ChAc), a rare neurodegenerative disorder. The altered RBC morphology likely influences their biomechanical properties which are crucial for the cells to pass the microvasculature. Here, we investigated blood cell deformability of 5 ChAc patients compared to healthy controls during up to one-year individual off-label treatment with the tyrosine kinases inhibitor dasatinib or several weeks with lithium. Measurements with two microfluidic techniques allowed us to assess RBC deformability under different shear stresses. Furthermore, we characterized leukocyte stiffness at high shear stresses. The results show that blood cell deformability - including both RBCs and leukocytes - in general is altered in ChAc patients compared to healthy donors. Therefore, this study shows for the first time an impairment of leukocyte properties in ChAc. During treatment with dasatinib or lithium, we observe alterations in RBC deformability and a stiffness increase for leukocytes. The hematological phenotype of ChAc patients hints at a reorganization of the cytoskeleton in blood cells which partly explains the altered mechanical properties observed here. These findings highlight the need for a systematic assessment of the contribution of impaired blood cell mechanics to the clinical manifestation of ChAc.

biophysics↗