Biology subjects

Gerke, J.

Publications and source records attributed to Gerke, J..

6 recordsLinked to original sources

bioRxiv2025

The VelB intrinsically disordered domain promotes selective heterodimer formation of velvet domain regulatory proteins for fungal development

Fungi possess several transcription factors with a characteristic velvet domain for DNA-binding and homo- or heterodimerization, which is structurally similar to the mammalian NF-B Rel homology domain. Velvet dimers control fungal development, virulence and mycotoxin formation. VelB is the only regulator, which carries an intrinsically disordered domain (IDD) within the velvet domain. The IDD as well as the positioning within VelB is conserved in the fungal kingdom. Intrinsically disordered regions contribute to transcription activation and DNA binding and frequently appear in eukaryotic transcription factors. The VelB IDD provides selective heterodimerization as well as protein stability control. The IDD is not required for the formation of the VelB-VeA heterodimer of Aspergillus nidulans or Verticillium dahliae, but promotes the formation of the VelB-VosA heterodimer. The IDD destabilizes VelB single molecules and also balances its distribution and ratio between both velvet heterodimers. These balances contribute to control appropriate mycotoxin production and sexual development. Herewith, the VelB IDD represents a novel control mechanism of velvet protein stability and heterodimer formation for precise priming of fungal development.

molecular biology↗

bioRxiv2025

The Aspergillus nidulans velvet domain containing transcription factor VeA is shuttled from cytoplasm into nucleus during vegetative growth and stays there for sexual development, but has to return into cytoplasm for asexual development

Survival of multicellular organisms requires the coordinated interplay between networks regulating gene expression and controlled intracellular transport of respective regulators. Velvet domain proteins are fungal transcription factors, which form various heterodimers and play key roles in controlling early developmental decisions towards more either asexual or sexual differentiation. VeA is the central subunit of the trimeric velvet complex VelB-VeA-LaeA, which links transcriptional to epigenetic control for the coordination of fungal developmental programs to specific secondary metabolite synthesis. Nuclear localization of the VeA bridging factor is carefully controlled in fungi. VeA carries three nuclear localization signals NLS1, NLS2 and NLS3, which all contribute to nuclear import. An additional VeA nuclear export sequence (NES) provides a shuttle function, which allows the cell to relocate VeA to the cytoplasm. VeA is nuclear during vegetative growth, but has to be exported from the nucleus to allow and promote asexual development. In contrast, progression of the sexual pathway requires continuous nuclear VeA localization. Accurate nuclear import and export control of velvet proteins is further connected to specific stability control mechanism as prerequisites for fungal development and secondary metabolism. These results illustrate the various complex mutual dependencies of velvet regulatory proteins for coordinating fungal development and secondary metabolism.

molecular biology↗

bioRxiv2025

Molecular circuit between Aspergillus nidulans transcription factors MsnA and VelB to coordinate fungal stress and developmental responses

Development and secondary metabolism of the filamentous fungus Aspergillus nidulans are tightly controlled by concerted actions of several master regulator transcription factors. The connection between fungal development and cellular stress response programs is often elusive. Here we show that the MsnA zinc finger transcription factor, which controls salt-stress response, is a novel major player in fungal development. A molecular circuit among MsnA and the velvet domain regulator VelB was discovered, which mutually fosters the actions of both regulatory proteins during development. MsnA controls the expression of several genes encoding master transcriptional regulators of asexual as well as sexual development. In addition, MsnA affects directly and indirectly the synthesis of specific secondary metabolites relevant for fungal defense against other organisms and growth, in addition to salt-stress responses. Moreover, the expression of genes encoding the epigenetic regulators VapA and VipC are also directly controlled by MsnA. These subunits of the VapA-VipC-VapB methyltransferase signal transduction complex promote asexual differentiation. MsnA is therefore placed at a novel prominent position of the central regulatory network, which coordinates stress responses with the developmental and metabolic fate of the fungus.

microbiology↗

bioRxiv2024

Microbial two front attack: elaborate root infections by Colletotrichum graminicola oval conidia during maize anthracnose

Most plant pathogenic microorganisms have evolved to infect distinct host tissues. The maize anthracnose fungus Colletotrichum graminicola is known for its ability to invade above-ground tissues with asexual falcate conidia. In addition, C. graminicola produces a second asexual spore type, oval conidia. This study investigates the specific adaptations that make oval conidia suitable for maize root infection, demonstrating that only oval conidia exhibit root pathogen characteristics. These include the ability to germinate in soil and grow chemotropically toward root-secreted molecules. High-performance liquid chromatography/mass spectrometry (HPLC/MS) analyses combined with biological assays indicate that diterpenoids, such as dihydrotanshinone I, are likely responsible for the chemical attraction of C. graminicola. Genetic analysis identified the a-pheromone receptor CgSte3 as responsible for diterpenoid perception by the fungal pathogen. In conclusion, the understanding of maize anthracnose disease must be expanded to include an elaborate root infection cycle by oval conidia.

microbiology↗

bioRxiv2021

Hülle-cell-mediated protection of fungal reproductive and overwintering structures against fungivorous animals

Fungal Hulle cells with nuclear storage and developmental backup functions are reminiscent of multipotent stem cells. In the soil, Hulle cells nurse the overwintering fruiting bodies of Aspergillus nidulans. The genome of A. nidulans harbors genes for the biosynthesis of xanthones. We show that enzymes and metabolites of this biosynthetic pathway accumulate in Hulle cells under the control of the regulatory velvet complex, which coordinates development and secondary metabolism. Deletion strains blocked in the conversion of anthraquinones to xanthones are delayed in maturation and growth of fruiting bodies. Xanthones are not required for sexual development but exert antifeedant effects on fungivorous animals such as springtails and woodlice. These findings reveal a novel role of Hulle cells in establishing secure niches for A. nidulans by accumulating metabolites with antifeedant activity that protect reproductive structures from animal predators.

biochemistry↗

bioRxiv2017

Parent-progeny imputation from pooled samples forcost-efficient genotyping in plant breeding

The increased usage of whole-genome selection (WGS) and other molecular evaluation methods in plant breeding relies on the ability to genotype a very large number of untested individuals in each breeding cycle. Many plant breeding programs evaluate large biparental populations of homozygous individuals derived from homozygous parent inbred lines. This structure lends itself to parent-progeny imputation, which transfers the genotype scores of the parents to progeny individuals that are genotyped for a much smaller number of loci. Here we introduce a parent-progeny imputation method that infers individual genotypes from index-free pooled samples of DNA of multiple individuals using a Hidden Markov Model (HMM). We demonstrated the method for pools of simulated maize double haploids (DH) from biparental populations, genotyped using a genotyping by sequencing (GBS) approach for 3,000 loci at 0.125x to 4x coverage. We observed high concordance between true and imputed marker scores and the HMM produced well-calibrated genotype probabilities that correctly reflected the uncertainty of the imputed scores. Genomic estimated breeding values (GEBV) calculated from the imputed scores closely matched GEBV calculated from the true marker scores. The within-population correlation between these sets of GEBV approached 0.95 at 1x and 4x coverage when pooling two or four individuals, respectively. Our approach can reduce the genotyping cost per individual by a factor up to the number of pooled individuals in GBS applications without the need for extra sequencing coverage, thereby enabling cost-effective large scale genotyping for applications such as WGS in plant breeding.

genetics↗