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The iron-containing porphyrin heme is of high interest for the food industry for the production of artificial meat as well as for medical applications, e.g. for anemia treatment. Recently, the biotechnological platform strain Corynebacterium glutamicum has emerged as a promising host for animal-free heme production. Beyond engineering of complex heme biosynthetic pathways, improving heme export offers significant yet untapped potential for enhancing production strains. In this study, a growth-coupled biosensor was designed to impose a selection pressure on the increased expression of the hrtBA operon encoding an ABC-type heme exporter in C. glutamicum. For this purpose, the promoter region PhrtB was replaced with that of the growth-regulating genes pfkA (phosphofructokinase) and aceE (pyruvate dehydrogenase), creating biosensor strains with a selection pressure for hrtBA activation. Resulting sensor strains were used for plate-based selections and for a repetitive batch f(luorescent)ALE using a robotics platform. Genome sequencing of isolated clones featuring increased hrtBA expression revealed three distinct mutational hotspots: (i) chrS, (ii) chrA, and (iii) cydD. Mutations in the genes of the ChrSA two-component system, which regulates hrtBA in response to heme levels, were identified as a promising target to enhance export activity. Furthermore, causal mutations within cydD, encoding an ABC-transporter essential for cytochrome bd oxidase assembly, were confirmed by the construction of a deletion mutant, which showed strongly increased hrtBA expression as well as increased cellular heme levels. These results further support the proposed role of CydDC as a heme transporter. Mutations identified in this study therefore underline the potential of biosensor-based growth coupling and provide promising engineering targets to improve microbial heme production.

PPD-H1 Improves Stress Resistance and Energy Metabolism to Boost Spike Fertility under High Ambient Temperatures

MAdLand Project - Erika Csicsely, Oguz Top, Wolfgang Frank et al.

This ARC accompanies the publication in Plant Journal: https://doi.org/10.1111/tpj.17236

DICER-LIKE (DCL) proteins play a central role in plant small RNA (sRNA) biogenesis. The genome of the early land plant Marchantia polymorpha encodes four DCL proteins: MpDCL1a, MpDCL1b, MpDCL3, and MpDCL4. While MpDCL1a, MpDCL3 and MpDCL4 show high similarities to their orthologs in Physcomitrium patens and Arabidopsis thaliana, MpDCL1b shares only a limited homology with PpDCL1b, but it is very similar, in terms of functional domains, to orthologs in other moss and fern species. We generated Mpdclge mutant lines for all MpDCL genes with the CRISPR/Cas9 system and conducted phenotypic analyses under control, salt stress, and phytohormone treatments to uncover specific MpDCL functions. The mutants displayed severe developmental aberrations, altered responses to salt and phytohormones, and disturbed sexual organ development. By combining mRNA and sRNA analyses, we demonstrate that MpDCLs and their associated sRNAs play pivotal roles in regulating development, abiotic stress tolerance and phytohormone response in M. polymorpha. We identified MpDCL1a in microRNA biogenesis, MpDCL4 in trans-acting small interfering RNA generation, and MpDCL3 in the regulation of pathogen-related genes. Notably, salt sensitivity in M. polymorpha is dependent on MpDCL1b and Mpdcl1bge mutants display enhanced tolerance and reduced miRNA expression in response to salt stress. We propose that M. polymorpha employs specific mechanisms for regulating MpDCL1b associated miRNAs under high salinity conditions, potentially shared with other species harboring MpDCL1b homologs.

Characterization of the FNR-type regulator GoxR

ARC repo for MARS testing

Global expression patterns of R-genes in tomato and potato

Traits linked to natural variation of sulfur content in Arabidopsis thaliana

Predmoter — cross-species prediction of plant promoter and enhancer regions

Exploring natural genetic variation in photosynthesis-related traits of barley in the field

Multi-Modal Rat MRI + Light Sheet Brain Dataset

A systematic overexpression approach reveals native targets to increase squalene production in Synechocystis sp. PCC 6803

Sugar transporters spatially organize microbiota colonization along the longitudinal root axis of Arabidopsis

A GH81-type β-glucan-binding protein enhances colonization by mutualistic fungi in barley

Fungi hijack a ubiquitous plant apoplastic endoglucanase to release a ROS scavenging β-glucan decasaccharide to subvert immune responses

Kinetic data for modeling the dynamics of the enzymes involved in animal fatty acid synthesis