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Publikation

Dahiya, P.; Bürstenbinder, K.; The making of a ring: Assembly and regulation of microtubule-associated proteins during preprophase band formation and division plane set-up Curr. Opin. Plant Biol. 73, 102366, (2023) DOI: 10.1016/j.pbi.2023.102366

The preprophase band (PPB) is a transient cytokinetic structure that marks the future division plane at the onset of mitosis. The PPB forms a dense cortical ring of mainly microtubules, actin filaments, endoplasmic reticulum, and associated proteins that encircles the nucleus of mitotic cells. After PPB disassembly, the positional information is preserved by the cortical division zone (CDZ). The formation of the PPB and its contribution to timely CDZ set-up involves activities of functionally distinct microtubule-associated proteins (MAPs) that interact physically and genetically to support robust division plane orientation in plants. Recent studies identified two types of plant-specific MAPs as key regulators of PPB formation, the TON1 RECRUITMENT MOTIF (TRM) and IQ67 DOMAIN (IQD) families. Both families share hallmarks of disordered scaffold proteins. Interactions of IQDs and TRMs with multiple binding partners, including the microtubule severing KATANIN1, may provide a molecular framework to coordinate PPB formation, maturation, and disassembly.
Publikation

Nietzschmann, L.; Smolka, U.; Perino, E. H. B.; Gorzolka, K.; Stamm, G.; Marillonnet, S.; Bürstenbinder, K.; Rosahl, S.; The secreted PAMP-induced peptide StPIP1_1 activates immune responses in potato Sci. Rep. 13, 20534, (2023) DOI: 10.1038/s41598-023-47648-x

Treatment of potato plants with the pathogen-associated molecular pattern Pep-13 leads to the activation of more than 1200 genes. One of these, StPIP1_1, encodes a protein of 76 amino acids with sequence homology to PAMP-induced secreted peptides (PIPs) from Arabidopsis thaliana. Expression of StPIP1_1 is also induced in response to infection with Phytophthora infestans, the causal agent of late blight disease. Apoplastic localization of StPIP1_1-mCherry fusion proteins is dependent on the presence of the predicted signal peptide. A synthetic peptide corresponding to the last 13 amino acids of StPIP1_1 elicits the expression of the StPIP1_1 gene itself, as well as that of pathogenesis related genes. The oxidative burst induced by exogenously applied StPIP1_1 peptide in potato leaf disks is dependent on functional StSERK3A/B, suggesting that StPIP1_1 perception occurs via a receptor complex involving the co-receptor StSERK3A/B. Moreover, StPIP1_1 induces expression of FRK1 in Arabidopsis in an RLK7-dependent manner. Expression of an RLK from potato with high sequence homology to AtRLK7 is induced by StPIP1_1, by Pep-13 and in response to infection with P. infestans. These observations are consistent with the hypothesis that, upon secretion, StPIP1_1 acts as an endogenous peptide required for amplification of the defense response.
Preprints

Bao, Z.; Guo, Y.; Deng, Y.; Zang, J.; Zhang, J.; Ouyang, B.; Qu, X.; Bürstenbinder, K.; Wang, P.; The microtubule-associated protein SlMAP70 interacts with SlIQD21 and regulates fruit shape formation in tomato (2022) DOI: 10.1101/2022.08.08.503161

The shape of tomato fruits is closely correlated to microtubule organization and the activity of microtubule associated proteins (MAP), but insights into the mechanism from a cell biology perspective are still largely elusive. Analysis of tissue expression profiles of different microtubule regulators revealed that functionally distinct classes of MAPs are highly expressed during fruit development. Among these, several members of the plant-specific MAP70 family are preferably expressed at the initiation stage of fruit development. Transgenic tomato lines overexpressing SlMAP70 produced elongated fruits that show reduced cell circularity and microtubule anisotropy, while SlMAP70 loss-of-function mutant showed an opposite effect with flatter fruits. Microtubule anisotropy of fruit endodermis cells exhibited dramatic rearrangement during tomato fruit development, and SlMAP70-1 is likely implicated in cortical microtubule organization and fruit elongation throughout this stage by interacting with SUN10/SlIQD21a. The expression of SlMAP70 (or co-expression of SlMAP70 and SUN10/SlIQD21a) induces microtubule stabilization and prevents its dynamic rearrangement, both activities are essential for fruit shape establishment after anthesis. Together, our results identify SlMAP70 as a novel regulator of fruit elongation, and demonstrate that manipulating microtubule stability and organization at the early fruit developmental stage has a strong impact on fruit shape.
Publikation

Bao, Z.; Xu, Z.; Zang, J.; Bürstenbinder, K.; Wang, P.; The Morphological Diversity of Plant Organs: Manipulating the Organization of Microtubules May Do the Trick Front Cell Dev Biol 9, 649626, (2021) DOI: 10.3389/fcell.2021.649626

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Bücher und Buchkapitel

Poeschl, Y.; Möller, B.; Müller, L.; Bürstenbinder, K.; User-friendly assessment of pavement cell shape features with PaCeQuant: Novel functions and tools (Charles T. Anderson, Elizabeth S. Haswell, Ram Dixit). Methods Cell Biol. 160, 349-363, (2020) DOI: 10.1016/bs.mcb.2020.04.010

Leaf epidermis pavement cells develop complex jigsaw puzzle-like shapes in many plant species, including the model plant Arabidopsis thaliana. Due to their complex morphology, pavement cells have become a popular model system to study shape formation and coordination of growth in the context of mechanically coupled cells at the tissue level. To facilitate robust assessment and analysis of pavement cell shape characteristics in a high-throughput fashion, we have developed PaCeQuant and a collection of supplemental tools. The ImageJ-based MiToBo plugin PaCeQuant supports fully automatic segmentation of cell contours from microscopy images and the extraction of 28 shape features for each detected cell. These features now also include the Largest Empty Circle criterion as a proxy for mechanical stress. In addition, PaCeQuant provides a set of eight features for individual lobes, including the categorization as type I and type II lobes at two- and three-cell junctions, respectively. The segmentation and feature extraction results of PaCeQuant depend on the quality of input images. To allow for corrections in case of local segmentation errors, the LabelImageEditor is provided for user-friendly manual postprocessing of segmentation results. For statistical analysis and visualization, PaCeQuant is supplemented with the R package PaCeQuantAna, which provides statistical analysis functions and supports the generation of publication-ready plots in ready-to-use R workflows. In addition, we recently released the FeatureColorMapper tool which overlays feature values over cell regions for user-friendly visual exploration of selected features in a set of analyzed cells.
Publikation

Naumann, C.; Müller, J.; Sakhonwasee, S.; Wieghaus, A.; Hause, G.; Heisters, M.; Bürstenbinder, K.; Abel, S.; The Local Phosphate Deficiency Response Activates Endoplasmic Reticulum Stress-Dependent Autophagy Plant Physiol. 179, 460-476, (2019) DOI: 10.1104/pp.18.01379

Inorganic phosphate (Pi) is often a limiting plant nutrient. In members of the Brassicaceae family, such as Arabidopsis (Arabidopsis thaliana), Pi deprivation reshapes root system architecture to favor topsoil foraging. It does so by inhibiting primary root extension and stimulating lateral root formation. Root growth inhibition from phosphate (Pi) deficiency is triggered by iron-stimulated, apoplastic reactive oxygen species generation and cell wall modifications, which impair cell-to-cell communication and meristem maintenance. These processes require LOW PHOSPHATE RESPONSE1 (LPR1), a cell wall-targeted ferroxidase, and PHOSPHATE DEFICIENCY RESPONSE2 (PDR2), the single endoplasmic reticulum (ER)-resident P5-type ATPase (AtP5A), which is thought to control LPR1 secretion or activity. Autophagy is a conserved process involving the vacuolar degradation of cellular components. While the function of autophagy is well established under nutrient starvation (C, N, or S), it remains to be explored under Pi deprivation. Because AtP5A/PDR2 likely functions in the ER stress response, we analyzed the effect of Pi limitation on autophagy. Our comparative study of mutants defective in the local Pi deficiency response, ER stress response, and autophagy demonstrated that ER stress-dependent autophagy is rapidly activated as part of the developmental root response to Pi limitation and requires the genetic PDR2-LPR1 module. We conclude that Pi-dependent activation of autophagy in the root apex is a consequence of local Pi sensing and the associated ER stress response, rather than a means for systemic recycling of the macronutrient.
Publikation

Bürstenbinder, K.; Möller, B.; Plötner, R.; Stamm, G.; Hause, G.; Mitra, D.; Abel, S.; The IQD Family of Calmodulin-Binding Proteins Links Calcium Signaling to Microtubules, Membrane Subdomains, and the Nucleus Plant Physiol. 173, 1692-1708, (2017) DOI: 10.1104/pp.16.01743

Calcium (Ca2+) signaling and dynamic reorganization of the cytoskeleton are essential processes for the coordination and control of plant cell shape and cell growth. Calmodulin (CaM) and closely related calmodulin-like (CML) polypeptides are principal sensors of Ca2+ signals. CaM/CMLs decode and relay information encrypted by the second messenger via differential interactions with a wide spectrum of targets to modulate their diverse biochemical activities. The plant-specific IQ67 DOMAIN (IQD) family emerged as possibly the largest class of CaM-interacting proteins with undefined molecular functions and biological roles. Here, we show that the 33 members of the IQD family in Arabidopsis (Arabidopsis thaliana) differentially localize, using green fluorescent protein (GFP)-tagged proteins, to multiple and distinct subcellular sites, including microtubule (MT) arrays, plasma membrane subdomains, and nuclear compartments. Intriguingly, the various IQD-specific localization patterns coincide with the subcellular patterns of IQD-dependent recruitment of CaM, suggesting that the diverse IQD members sequester Ca2+-CaM signaling modules to specific subcellular sites for precise regulation of Ca2+-dependent processes. Because MT localization is a hallmark of most IQD family members, we quantitatively analyzed GFP-labeled MT arrays in Nicotiana benthamiana cells transiently expressing GFP-IQD fusions and observed IQD-specific MT patterns, which point to a role of IQDs in MT organization and dynamics. Indeed, stable overexpression of select IQD proteins in Arabidopsis altered cellular MT orientation, cell shape, and organ morphology. Because IQDs share biochemical properties with scaffold proteins, we propose that IQD families provide an assortment of platform proteins for integrating CaM-dependent Ca2+ signaling at multiple cellular sites to regulate cell function, shape, and growth.
Publikation

Abel, S.; Bürstenbinder, K.; Müller, J.; The emerging function of IQD proteins as scaffolds in cellular signaling and trafficking Plant Signal Behav. 8, e24369, (2013) DOI: 10.4161/psb.24369

Calcium (Ca2+) signaling modules are essential for adjusting plant growth and performance to environmental constraints. Differential interactions between sensors of Ca2+ dynamics and their molecular targets are at the center of the transduction process. Calmodulin (CaM) and CaM-like (CML) proteins are principal Ca2+-sensors in plants that govern the activities of numerous downstream proteins with regulatory properties. The families of IQ67-Domain (IQD) proteins are a large class of plant-specific CaM/CML-targets (e.g., 33 members in A. thaliana) which share a unique domain of multiple varied CaM retention motifs in tandem orientation. Genetic studies in Arabidopsis and tomato revealed first roles for IQD proteins related to basal defense response and plant development. Molecular, biochemical and histochemical analysis of Arabidopsis IQD1 demonstrated association with microtubules as well as targeting to the cell nucleus and nucleolus. In vivo binding to CaM and kinesin light chain-related protein-1 (KLCR1) suggests a Ca2+-regulated scaffolding function of IQD1 in kinesin motor-dependent transport of multiprotein complexes. Furthermore, because IQD1 interacts in vitro with single-stranded nucleic acids, the prospect arises that IQD1 and other IQD family members facilitate cellular RNA localization as one mechanism to control and fine-tune gene expression and protein sorting.
Publikation

Carbonell, A.; Flores, R.; Gago, S.; Trans-cleaving hammerhead ribozymes with tertiary stabilizing motifs: in vitro and in vivo activity against a structured viroid RNA Nucleic Acids Res. 39, 2432-2444, (2011) DOI: 10.1093/nar/gkq1051

Trans -cleaving hammerheads with discontinuous or extended stem I and with tertiary stabilizing motifs (TSMs) have been tested previously against short RNA substrates in vitro at low Mg 2+ concentration. However, the potential of these ribozymes for targeting longer and structured RNAs in vitro and in vivo has not been examined. Here, we report the in vitro cleavage of short RNAs and of a 464-nt highly structured RNA from potato spindle tuber viroid (PSTVd) by hammerheads with discontinuous and extended formats at submillimolar Mg 2+ . Under these conditions, hammerheads derived from eggplant latent viroid and peach latent mosaic viroid (PLMVd) with discontinuous and extended formats, respectively, where the most active. Furthermore, a PLMVd-derived hammerhead with natural TSMs showed activity in vivo against the same long substrate and interfered with systemic PSTVd infection, thus reinforcing the idea that this class of ribozymes has potential to control pathogenic RNA replicons.
Publikation

Flores, R.; Gas, M.-E.; Molina-Serrano, D.; Nohales, M.-?.; Carbonell, A.; Gago, S.; De la Peña, M.; Daròs, J.-A.; Viroid Replication: Rolling-Circles, Enzymes and Ribozymes Viruses 1, 317-334, (2009) DOI: 10.3390/v1020317

Viroids, due to their small size and lack of protein-coding capacity, must rely essentially on their hosts for replication. Intriguingly, viroids have evolved the ability to replicate in two cellular organella, the nucleus (family Pospiviroidae) and the chloroplast (family Avsunviroidae). Viroid replication proceeds through an RNA-based rolling-circle mechanism with three steps that, with some variations, operate in both polarity strands: i) synthesis of longer-than-unit strands catalyzed by either the nuclear RNA polymerase II or a nuclear-encoded chloroplastic RNA polymerase, in both instances redirected to transcribe RNA templates, ii) cleavage to unit-length, which in the family Avsunviroidae is mediated by hammerhead ribozymes embedded in both polarity strands, while in the family Pospiviroidae the oligomeric RNAs provide the proper conformation but not the catalytic activity, and iii) circularization. The host RNA polymerases, most likely assisted by additional host proteins, start transcription from specific sites, thus implying the existence of viroid promoters. Cleavage and ligation in the family Pospiviroidae is probably catalyzed by an RNase III-like enzyme and an RNA ligase able to circularize the resulting 5’ and 3’ termini. Whether a chloroplastic RNA ligase mediates circularization in the family Avsunviroidae, or this reaction is autocatalytic, remains an open issue.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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