Biology subjects

Hartwig, C.

Publications and source records attributed to Hartwig, C..

7 recordsLinked to original sources

bioRxiv2025

Tryptophan-Driven Metabolomic Shift in Acidobacteriaceae Reveals Phytohormones and Antifungal Metabolites

Acidobacteriota is one of the most abundant phyla in soils and has recently attracted attention for its potential role in promoting phytosanitary benefits. The metabolomic capabilities of this phylum remain poorly characterised, with few experimentally confirmed metabolites described. To address these gaps, we combined metabolomic profiling with comparative genomic analysis to explore the functional potential of novel strains within the Acidobacteriaceae family. Genome mining across the phylum for plant-growth-promoting traits revealed the presence and taxon-specific enrichment of genes related to phytohormone production, as well as other genes associated with plant-beneficial microorganisms. When tryptophan was added to the cultivation medium, it triggered a strong metabolic response in the strains, resulting in measurable changes in the production levels of phytohormones such as indole-3-acetic acid and indole-3-pyruvate. Building on these findings, we examined the metabolic reprogramming caused by tryptophan supplementation, which suppressed the growth of phytopathogenic fungi, leading to the identification of malassezindoles and pityriacitrins as active agents. This was confirmed by isolating and elucidating the structure of pityriacitrin B and one of its methyl esters through NMR studies. Overall, these findings shed light on the previously unexplored metabolic potential of the Acidobacteriota phylum, emphasising its ecological importance for phytosanitary applications. ImportanceDespite their ubiquity and genomic diversity, the functional metabolism of members of the Acidobacteriota has largely remained uncharacterised. This study links genomic predictions to experimentally verified metabolomic outputs of Acidobacteriaceae, demonstrating tryptophan-responsive metabolic shifts translating to phytohormones and metabolites suppressing fungal growth. Our work underscores the emerging role of Acidobacteriota as important contributors to soil ecosystem functioning and plant-microbe interactions.

microbiology↗

bioRxiv2024

Liquid footprinting: A novel approach for DNA footprinting using short double-stranded cell-free DNA from plasma

The diagnostic potential of short double-stranded cell-free DNA (cfDNA) in blood plasma has not been recognized, yet. Here, we present a method for enrichment of double-stranded cfDNA with an average length of about 40 base pairs from cfDNA for high-throughput DNA sequencing. This class of cfDNA is enriched at gene promoters and binding sites of transcription factors or structural DNA-binding proteins, so that a genome-wide DNA footprint is directly captured from liquid biopsies. In short double-stranded cfDNA from healthy individuals, we found significant enrichment of 203 transcription factor motifs. Additionally, short double-stranded cfDNA signals at specific genomic regions correlate negatively with DNA-methylation, positively with H3K4me3 histone modifications and gene transcription. When comparing short double-stranded cfDNA from patient samples of pancreatic ductal adenocarcinoma with colorectal carcinoma or septic with post-operative controls, we identified 731 and 1,107 differentially enriched loci, respectively. Using these differentially enriched loci, the disease types can be clearly distinguished by principal component analysis demonstrating the diagnostic potential of short double-stranded cfDNA signals as a new class of biomarkers for liquid biopsies.

genomics↗

bioRxiv2021

Genomic and chemical decryption of the Bacteroidetes phylum for its potential to biosynthesize natural products

With progress in genome sequencing and data sharing, 1000s of bacterial genomes are publicly available. Genome mining - using bioinformatics tools in terms of biosynthetic gene cluster (BGC) identification, analysis and rating - has become a key technology to explore the capabilities for natural product (NP) biosynthesis. Comprehensively, analyzing the genetic potential of the phylum Bacteroidetes revealed Chitinophaga as the most talented genus in terms of BGC abundance and diversity. Guided by the computational predictions, we conducted a metabolomics and bioactivity driven NP discovery program on 25 Chitinophaga strains. High numbers of peerless strain-specific metabolite buckets confirmed the upfront predicted biosynthetic potential and revealed a tremendous uncharted chemical space. Sourcing this dataset, we isolated the new iron chelating nonribosomally-synthesized cyclic tetradeca- and pentadecalipodepsipeptide antibiotics chitinopeptins with activity against Candida, produced by C. eiseniae DSM 22224 and C. flava KCTC 62435, respectively. TeaserCombination of omics-technologies revealed taxonomical hotspots for specialized metabolites within Bacteroidetes.

microbiology↗

bioRxiv2020

Predation drives specialized host plant associations in preadapted milkweed bugs (Heteroptera: Lygaeinae)

Host plant specialization across herbivorous insects varies dramatically, but the underlying evolutionary mechanisms are little-known. The milkweed bugs (Heteroptera: Lygaeinae) are ancestrally associated with plants of the Apocynaceae from which they commonly sequester cardiac glycosides for defense, facilitated by resistant Na+/K+-ATPases and adaptations for transport, storage and discharge of toxins. Here, we show that three Lygaeinae species independently colonized four novel non-apocynaceous hosts, convergently producing cardiac glycosides. A fourth species shifted to a new source of toxins by tolerating and sequestering alkaloids from meadow saffron (Colchicum autumnale, Colchicaceae). Across three species tested, feeding on seeds containing toxins did not improve growth, but sequestration mediated protection against predatory lacewing larvae and birds. We conclude that physiological preadaptations and convergent phytochemistry facilitated novel specialized host associations. Therefore, selection by predators on sequestration of defenses, rather than the exploitation of novel dietary resources, can lead to obligatory specialized host associations in generalist insects.

evolutionary biology↗

bioRxiv2020

Golgi-Dependent Copper Homeostasis Sustains Synaptic Development and Mitochondrial Content

Rare genetic diseases preponderantly affect the nervous system with phenotypes spanning from neurodegeneration to neurodevelopmental disorders. This is the case for both Menkes and Wilson disease, arising from mutations in ATP7A and ATP7B, respectively. The ATP7A and ATP7B proteins localize to the Golgi and regulate copper homeostasis. We demonstrate conserved interactions between ATP7 paralogs with the COG complex, a Golgi complex tether. Disruption of Drosophila copper homeostasis by ATP7 tissue-specific transgenic expression caused alterations in epidermis, catecholaminergic, sensory, and motor neurons. Prominent among neuronal phenotypes was a decreased mitochondrial content at synapses, a phenotype that paralleled with alterations of synaptic morphology, transmission, and plasticity. These neuronal and synaptic phenotypes caused by transgenic expression of ATP7 were rescued by downregulation or haploinsufficiency of COG complex subunits. We conclude that the integrity of Golgi-dependent copper homeostasis mechanisms, requiring ATP7 and COG, are necessary to maintain mitochondria functional integrity and localization to synapses. Significance StatementMenkes and Wilson disease affect copper homeostasis and characteristically afflict the nervous system. However, their molecular neuropathology mechanisms remain mostly unexplored. We demonstrate that copper homeostasis in neurons is maintained by two factors that localize to the Golgi apparatus, ATP7 and the COG complex. Disruption of these mechanisms affect mitochondrial function and localization to synapses as well as neurotransmission and synaptic plasticity. These findings suggest a new principle of interorganelle communication whereby the Golgi apparatus and mitochondria are functionally coupled through homeostatically controlled cellular copper levels.

neuroscience↗

bioRxiv2020

Mitochondrial Proteostasis Requires Genes Encoded in a Neurodevelopmental Syndrome Locus that are Necessary for Synapse Function

Eukaryotic cells maintain proteostasis through mechanisms that require cytoplasmic and mitochondrial translation. Genetic defects affecting cytoplasmic translation perturb synapse development, neurotransmission, and are causative of neurodevelopmental disorders such as Fragile X syndrome. In contrast, there is little indication that mitochondrial proteostasis, either in the form of mitochondrial protein translation and/or degradation, is required for synapse development and function. Here we focus on two genes deleted in a recurrent copy number variation causing neurodevelopmental disorders, the 22q11.2 microdeletion syndrome. We demonstrate that SLC25A1 and MRPL40, two genes present in this microdeleted segment and whose products localize to mitochondria, interact and are necessary for mitochondrial protein translation and proteostasis. Our Drosophila studies show that mitochondrial ribosome function is necessary for synapse neurodevelopment, function, and behavior. We propose that mitochondrial proteostasis perturbations, either by genetic or environmental factors, are a novel pathogenic mechanism for neurodevelopmental disorders.

neuroscience↗

bioRxiv2018

Systems Analysis of the 22q11.2 Microdeletion Syndrome Converges on a Mitochondrial Interactome Necessary for Synapse Function and Behavior

Neurodevelopmental disorders offer insight into synaptic mechanisms. To unbiasedly uncover these mechanisms, we studied the 22q11.2 syndrome, a recurrent copy number variant, which is the highest schizophrenia genetic risk factor. We quantified the proteomes of 22q11.2 mutant human fibroblasts and mouse brains carrying a 22q11.2-like defect, Df(16)A+/-. Molecular ontologies defined mitochondrial compartments and pathways as some of top ranked categories. In particular, we identified perturbations in the SLC25A1-SLC25A4 mitochondrial transporter interactome as associated with the 22q11.2 genetic defect. Expression of SLC25A1-SLC25A4 interactome components was affected in neuronal cells from schizophrenia patients. Furthermore, hemideficiency of the Drosophila SLC25A4 orthologue, dSLC25A4-sesB, affected synapse function and impaired sleep patterns in a neuronal-specific manner. These results identify a novel synaptic role of mitochondrial inner membrane solute transporters. We propose that mitochondria are among key organelles affected by genetic defects that increase the risk of neurodevelopmental disorders.

neuroscience↗