Publications by authors named "Steven Jacobsen"

Proteins are localized and concentrated at cellular and genomic locations for specific and efficient functions. Efforts to understand protein accumulation in eukaryotic organisms have primarily focused on multivalent interactions between intrinsically disordered regions (IDRs) as mediators of protein condensation. We previously showed that α-crystalline domain (ACD) proteins 15 (ACD15) and 21 (ACD21) were required for multimerization and the accumulation of gene-silencing methyl-CpG-binding domain protein 6 (MBD6) at chromocenters in .

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Unstable transcripts have emerged as markers of active enhancers in vertebrates and shown to be involved in many cellular processes and medical disorders. However, their prevalence and role in plants is largely unexplored. Here, we comprehensively captured all actively initiating (nascent) transcripts across diverse crops and other plants using capped small (cs)RNA sequencing.

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Silencing pathways prevent transposable element (TE) proliferation and help to maintain genome integrity through cell division. Silenced genomic regions can be classified as either euchromatic or heterochromatic, and are targeted by genetically separable epigenetic pathways. In plants, the RNA-directed DNA methylation (RdDM) pathway targets mostly euchromatic regions, while CMT DNA methyltransferases are mainly associated with heterochromatin.

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DNA methylation is an essential component of transposable element (TE) silencing, yet the mechanism by which methylation causes transcriptional repression remains poorly understood. Here we study the Arabidopsis thaliana Methyl-CpG Binding Domain (MBD) proteins MBD1, MBD2 and MBD4 and show that MBD2 acts as a TE repressor during male gametogenesis. MBD2 bound chromatin regions containing high levels of CG methylation, and MBD2 was capable of silencing the FWA gene when tethered to its promoter.

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The H3 methyltransferases ATXR5 and ATXR6 deposit H3.1K27me1 to heterochromatin to prevent genomic instability and transposon re-activation. Here, we report that atxr5 atxr6 mutants display robust resistance to Geminivirus.

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DNA methylation mediates silencing of transposable elements and genes in part via recruitment of the Arabidopsis MBD5/6 complex, which contains the methyl-CpG binding domain (MBD) proteins MBD5 and MBD6, and the J-domain containing protein SILENZIO (SLN). Here, we characterize two additional complex members: α-crystalline domain (ACD) containing proteins ACD15 and ACD21. We show that they are necessary for gene silencing, bridge SLN to the complex, and promote higher-order multimerization of MBD5/6 complexes within heterochromatin.

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Comparison of biosynthetic gene clusters (BGCs) found in devastating plant pathogens and biocontrol fungi revealed an uncharacterized and conserved polyketide BGC. Genome mining identified the associated metabolite to be treconorin, which has a terpene-like, fused 5,7-bicyclic core that is proposed to derive from a (4 + 3) cycloaddition. The core is esterified with d-glucose, which derives from the glycosidic cleavage of a trehalose ester precursor.

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Unstable transcripts have emerged as markers of active enhancers in vertebrates and shown to be involved in many cellular processes and medical disorders. However, their prevalence and role in plants is largely unexplored. Here, we comprehensively captured all actively initiating ("nascent") transcripts across diverse crops and other plants using capped small (cs)RNA-seq.

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Article Synopsis
  • In animals, piRNAs work with PIWI proteins to silence transposons, and in species like Drosophila, these RNAs are passed from mother to offspring to kickstart piRNA production.
  • This research focuses on the Y-linked piRNA locus Su(Ste) in Drosophila, demonstrating that its piRNAs are generated in male germlines and initiated by maternal transposon piRNAs.
  • The study reveals that when XXY mothers deposit Su(Ste) piRNAs, it eliminates the need for sons to produce their own, showcasing a unique way mothers can shield their male offspring through genetic mechanisms.
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DNA methylation mediates silencing of transposable elements and genes in part via recruitment of the Arabidopsis MBD5/6 complex, which contains the methyl-CpG-binding domain (MBD) proteins MBD5 and MBD6, and the J-domain containing protein SILENZIO (SLN). Here we characterize two additional complex members: α-crystalline domain containing proteins ACD15 and ACD21. We show that they are necessary for gene silencing, bridge SLN to the complex, and promote higher order multimerization of MBD5/6 complexes within heterochromatin.

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Natural products biosynthesized from biocontrol fungi in the rhizosphere can have both beneficial and deleterious effects on plants. Herein, we performed a comprehensive analysis of natural product biosynthetic gene clusters (BGCs) from the widely used biocontrol fungus T22 (ThT22). This fungus encodes at least 64 BGCs, yet only seven compounds and four BGCs were previously characterized or mined.

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MORPHEUS' MOLECULE1 (MOM1) is an Arabidopsis factor previously shown to mediate transcriptional silencing independent of major DNA methylation changes. Here we find that MOM1 localizes with sites of RNA-directed DNA methylation (RdDM). Tethering MOM1 with an artificial zinc finger to an unmethylated FWA promoter leads to establishment of DNA methylation and FWA silencing.

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Proteins and enzymes generally achieve their functions by creating well-defined 3D architectures that pre-organize reactive functionalities. Mimicking this approach to supramolecular pre-organization is leading to the development of highly versatile artificial chemical environments, including new biomaterials, medicines, artificial enzymes, and enzyme-like catalysts. The use of β-turn and α-helical motifs is one approach that enables the precise placement of reactive functional groups to enable selective substrate activation and reactivity/selectivity that approaches natural enzymes.

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Article Synopsis
  • HepB-CpG (Heplisav-B) is a hepatitis B vaccine that requires only 2 doses, while HepB-alum (Engerix-B) requires 3 doses, prompting a study to assess the safety of these vaccines regarding new immune-mediated diseases, herpes zoster, and anaphylaxis in a real-world setting.
  • A cohort study followed 69,625 adults who received either vaccine between 2018 and 2019, using electronic health records to track the incidence of the specified outcomes for 13 months.
  • Results showed similar rates of immune-mediated diseases between both vaccines, except for rheumatoid arthritis, which was initially higher for HepB-CpG but adjusted to show no significant difference after
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Silencing pathways prevent transposable element (TE) proliferation and help to maintain genome integrity through cell division. Silenced genomic regions can be classified as either euchromatic or heterochromatic, and are targeted by genetically separable epigenetic pathways. In plants, the RNA-directed DNA methylation (RdDM) pathway targets mostly euchromatic regions, while CMT DNA methyltransferases are mainly associated with heterochromatin.

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Background: The microrchidia (MORC) proteins are a family of evolutionarily conserved GHKL-type ATPases involved in chromatin compaction and gene silencing. Arabidopsis MORC proteins act in the RNA-directed DNA methylation (RdDM) pathway, where they act as molecular tethers to ensure the efficient establishment of RdDM and de novo gene silencing. However, MORC proteins also have RdDM-independent functions although their underlying mechanisms are unknown.

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Arabidopsis telomeric repeat binding factors (TRBs) can bind telomeric DNA sequences to protect telomeres from degradation. TRBs can also recruit Polycomb Repressive Complex 2 (PRC2) to deposit tri-methylation of H3 lysine 27 (H3K27me3) over certain target loci. Here, we demonstrate that TRBs also associate and colocalize with JUMONJI14 (JMJ14) and trigger H3K4me3 demethylation at some loci.

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In addition to the conserved RNA polymerases I to III (Pols I to III) in eukaryotes, two atypical polymerases, Pols IV and V, specifically produce noncoding RNA in the RNA-directed DNA methylation pathway in plants. Here, we report on the structures of cauliflower Pol V in the free and elongation conformations. A conserved tyrosine residue of NRPE2 stacks with a double-stranded DNA branch of the transcription bubble to potentially attenuate elongation by inducing transcription stalling.

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DNA methylation has been utilized for target gene silencing in plants. However, it is not well understood whether other silencing pathways can be also used to manipulate gene expression. Here we performed a gain-of-function screen for proteins that could silence a target gene when fused to an artificial zinc finger.

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MOM1 is an factor previously shown to mediate transcriptional silencing independent of major DNA methylation changes. Here we found that MOM1 localizes with sites of RNA-directed DNA methylation (RdDM). Tethering MOM1 with artificial zinc finger to unmethylated promoter led to establishment of DNA methylation and silencing.

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Article Synopsis
  • CRISPR-Cas systems, specifically the hypercompact CasΦ nuclease, are effective tools for creating stable gene edits in plants.
  • CasΦ guide RNAs can be expressed using different promoters, with higher efficiency observed when targeting non-methylated DNA regions.
  • Variants of CasΦ, named vCasΦ and nCasΦ, outperform wild-type CasΦ in editing efficiency and show no off-target effects, making CasΦ a promising addition to plant genome editing techniques.
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Pathogens rely on expression of host susceptibility (S) genes to promote infection and disease. As DNA methylation is an epigenetic modification that affects gene expression, blocking access to S genes through targeted methylation could increase disease resistance. Xanthomonas phaseoli pv.

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The introduction of volatile-rich subducting slabs to the mantle may locally generate large redox gradients, affecting phase stability, element partitioning and volatile speciation. Here we investigate the redox conditions of the deep mantle recorded in inclusions in a diamond from Kankan, Guinea. Enstatite (former bridgmanite), ferropericlase and a uniquely Mg-rich olivine (Mg# 99.

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Article Synopsis
  • CRISPR-Cas systems are mechanisms in microbes that protect against viral infections using adaptive RNA guidance, and researchers discovered these systems also exist in various bacteriophages.
  • Bacteriophage-encoded CRISPR systems include all six known types but some are missing key components, indicating they might serve different functions or rely on hosts for support.
  • The study introduces new Cas9-like proteins and the Casλ family, which has a unique structure for recognizing DNA and has shown potential for genome editing in plants and animals, emphasizing the importance of phage-derived CRISPR-Cas enzymes.
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Silencing of transposable elements (TEs) drives the evolution of numerous redundant mechanisms of transcriptional regulation. Arabidopsis MBD5, MBD6, and SILENZIO act as TE repressors downstream of DNA methylation. Here, we show, via single-nucleus RNA-seq of developing male gametophytes, that these repressors are critical for TE silencing in the pollen vegetative cell, a companion cell important for fertilization that undergoes chromatin decompaction.

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