Now showing items 1-20 of 4029

    • Intrinsic and acquired cancer immunotherapy resistance

      Saleh, Reem; Sasidharan Nair, Varun; Toor, Salman M.; Elkord, Eyad; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, VIC, Australia; Cancer Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha, Qatar;Department of Experimental Immunology, Helmholtz Centre for Infection Research, Braunschweig, Germany; Biomedical Research Center, School of Science, Engineering and Environment, University of Salford, Manchester, United Kingdom; College of Health and Life Sciences (CHLS), Hamad Bin Khalifa University (HBKU), Doha, Qatar;Natural and Medical Sciences Research Center, University of Nizwa, Nizwa, Oman (Elsevier, 2021-08-27)
      Cancer immunotherapies, such as immune checkpoint inhibitors (ICIs), have revolutionized the treatment of various cancers and have shown a great efficacy in inducing antitumor immunity. Cancer immunotherapy in the form of adoptive cell transfer (ACT) have also been developed to eradicate tumor cells in a specific and effective manner, and it includes the administration of autologous tumor-infiltrating T-cells (TILs), T-cell receptor (TCR)-modified T-cells, or genetically engineered chimeric antigen receptor (CAR)-specific T-cells (CARTs) in cancer patients. Additionally, cancer vaccines and recombinant cytokines can be used as monotherapy or adjuvant therapy. Despite the success of immunotherapies in treating various solid tumors and hematologic malignancies, a significant number of patients do not benefit from these therapies and exhibit limited or no response. Some cancer patients do not respond to immunotherapies as a result of primary or intrinsic tumor resistance, while others respond to immunotherapies but develop resistance over time, referred to as adaptive or acquired tumor resistance. Tumor intrinsic- and extrinsic-mediated mechanisms, including genetic and epigenetic alterations, tumor-mutational loads, overexpression of co-inhibitory immune checkpoints, and elevated levels of suppressive immune cells and cytokines, can lead to a compromised antitumor immunity favoring tumorigenesis and cancer progression. This chapter outlines mechanisms of intrinsic tumor resistance and the emergence of acquired tumor resistance to cancer immunotherapies. Moreover, this chapter describes combined cancer immunotherapies, which may offer a great therapeutic potential to overcome tumor resistance against therapy and improve clinical outcomes in cancer patients. +é(c) 2022 Elsevier Inc. All rights reserved
    • Alienimonas californiensis gen. nov. sp. nov., a novel Planctomycete isolated from the kelp forest in Monterey Bay.

      Boersma, Alje S; Kallscheuer, Nicolai; Wiegand, Sandra; Rast, Patrick; Peeters, Stijn H; Mesman, Rob J; Heuer, Anja; Boedeker, Christian; Jetten, Mike S M; Rohde, Manfred; et al. (2019-12-04)
      Planctomycetes are environmentally and biotechnologically important bacteria and are often found in association with nutrient-rich (marine) surfaces. To allow a more comprehensive understanding of planctomycetal lifestyle and physiology we aimed at expanding the collection of axenic cultures with new isolates. Here, we describe the isolation and genomic and physiological characterisation of strain CA12T obtained from giant bladder kelp (Macrocystis pyrifera) in Monterey Bay, California, USA. 16S rRNA gene sequence and whole genome-based phylogenetic analysis showed that strain CA12T clusters within the family Planctomycetaceae and that it has a high 16S rRNA sequence similarity (82.3%) to Planctomicrobium piriforme DSM 26348T. The genome of strain CA12T has a length of 5,475,215 bp and a G+C content of 70.1%. The highest growth rates were observed at 27 °C and pH 7.5. Using different microscopic methods, we could show that CA12T is able to divide by consecutive polar budding, without completing a characteristic planctomycetal lifestyle switch. Based on our data, we suggest that the isolated strain represents a novel species within a novel genus. We thus propose the name Alienimonas gen. nov. with Alienimonas californiensis sp. nov. as type species of the novel genus and CA12T as type strain of the novel species.
    • Description of three bacterial strains belonging to the new genus Novipirellula gen. nov., reclassificiation of Rhodopirellula rosea and Rhodopirellula caenicola and readjustment of the genus threshold of the phylogenetic marker rpoB for Planctomycetaceae.

      Kallscheuer, Nicolai; Wiegand, Sandra; Peeters, Stijn H; Jogler, Mareike; Boedeker, Christian; Heuer, Anja; Rast, Patrick; Jetten, Mike S M; Rohde, Manfred; Jogler, Christian (2019-12-19)
      Access to axenic cultures of Planctomycetes is crucial for further investigating their complex lifestyle, uncommon cell biology and primary and secondary metabolism. As a contribution to achieve this goal in the future, we here describe three strains belonging to the novel genus Novipirellula gen. nov. The strains were isolated from biotic and abiotic surfaces in the Baltic Sea and from the island Heligoland in the North Sea. Colony colours range from white to light pink. Cells are acorn-shaped and grew optimally at neutral pH and temperatures between 27 and 30 °C. Phylogenetic analyses revealed that the isolated strains represent three novel species belonging to a new genus, Novipirellula gen. nov. Beyond that, our analysis suggests that Rhodopirellula rosea LHWP3T, Rhodopirellula caenicola YM26-125T and Rhodopirellula maiorica SM1 are also members of this novel genus. Splitting the current genus Rhodopirellula into a more strictly defined genus Rhodopirellula and Novipirellula also allowed readjusting the genus threshold value for the gene rpoB, encoding the RNA polymerase β-subunit, which is used as phylogenetic marker for Planctomycetales. A threshold range of 75.5-78% identity of the analysed partial rpoB sequence turned out to be reliable for differentiation of genera within the family Planctomycetaceae.
    • Three novel Rubripirellula species isolated from plastic particles submerged in the Baltic Sea and the estuary of the river Warnow in northern Germany.

      Kallscheuer, Nicolai; Jogler, Mareike; Wiegand, Sandra; Peeters, Stijn H; Heuer, Anja; Boedeker, Christian; Jetten, Mike S M; Rohde, Manfred; Jogler, Christian (2019-12-05)
      Planctomycetes are a unique and important phylum containing mostly aquatic bacteria, which are often associated with phototrophic surfaces. A complex lifestyle, their potential for the production of bioactive small molecules, their unusual cell biology and a large number of giant and hypothetical genes in their genomes make these microorganisms a fascinating topic for further research. Here, we characterise three novel planctomycetal strains isolated from polystyrene and polyethylene particles that were submerged in the German part of the Baltic Sea and the estuary of the river Warnow. All three strains showed typical planctomycetal traits such as division by polar budding and formation of rosettes. The isolated strains were mesophilic and neutrophilic chemoheterotrophs and reached generation times of 10-25 h during laboratory-scale cultivation. Taxonomically, the three strains belong to the genus Rubripirellula. Based on our analyses all three strains represent novel species, for which we propose the names Rubripirellula amarantea sp. nov., Rubripirellula tenax sp. nov. and Rubripirellula reticaptiva sp. nov. The here characterised strains Pla22T (DSM 102267T = LMG 29691T), Poly51T (DSM 103356T = VKM B-3438T) and Poly59T (DSM 103767T = LMG 29696T) are the respective type strains of these novel species. We also emend the description of the genus Rubripirellula.
    • Dual-function chromogenic screening-based CRISPR/Cas9 genome editing system for actinomycetes.

      Wang, Qiushui; Xie, Feng; Tong, Yaojun; Habisch, Rebecca; Yang, Bowen; Zhang, Lixin; Müller, Rolf; Fu, Chengzhang (2019-12-02)
    • Towards the total synthesis of chondrochloren A: synthesis of the (Z)-enamide fragment.

      Geldsetzer, Jan; Kalesse, Markus (2020-04-14)
      The stereoselective synthesis of the (Z)-enamide fragment of chondrochloren (1) is described. A Buchwald-type coupling between amide 3 and (Z)-bromide 4 was used to generate the required fragment. The employed amide 3 comprising three chiral centers was obtained through a seven-step sequence starting from ᴅ-ribonic acid-1,4-lactone. The (Z)-vinyl bromide 4 is accessible in four steps from 4-hydroxybenzaldehyde. The pivotal cross coupling between both fragments was achieved after extensive experimentation with copper(I) iodide, K2CO3 and N,N'-dimethylethane-1,2-diamine.
    • Functional homo- and heterodimeric actin capping proteins from the malaria parasite.

      Bendes, Ábris Ádám; Chatterjee, Moon; Götte, Benjamin; Kursula, Petri; Kursula, Inari (2020-03-02)
    • MIAMI--a tool for non-targeted detection of metabolic flux changes for mode of action identification.

      Dudek, Christian-Alexander; Reuse, Carsten; Fuchs, Regine; Hendriks, Janneke; Starck, Veronique; Hiller, Karsten
    • Elimination of Staphylococcus aureus from the bloodstream using a novel biomimetic sorbent haemoperfusion device.

      Seffer, Malin-Theres; Eden, Gabriele; Engelmann, Susanne; Kielstein, Jan T (2020-08-24)
      Removal of bacteria from the blood by means of extracorporeal techniques has been attempted for decades. In late 2019, the European Union licensed the first ever haemoperfusion device for removal of bacteria from the blood. The active ingredient of Seraph 100 Microbind Affinity Blood Filter is ultrahigh molecular weight polyethylene beads with endpoint-attached heparin. Bacteria have been shown to bind to heparin as they would usually do to the heparan sulfate on the cell surface, thereby being removed from the blood stream. We describe the first case of a female chronic haemodialysis patient in which this device was clinically used for a Staphylococcus aureus infection that persisted for 4 days despite antibiotic therapy. After a single treatment, the bacterial load decreased and the blood cultures at the end of a 4 hour haemoperfusion exhibited no bacterial growth.
    • Mitochondria: at the crossroads of regulating lung epithelial cell function in chronic obstructive pulmonary disease.

      Aghapour, Mahyar; Remels, Alexander H V; Pouwels, Simon D; Bruder, Dunja; Hiemstra, Pieter S; Cloonan, Suzanne M; Heijink, Irene H (2019-11-06)
      Disturbances in mitochondrial structure and function in lung epithelial cells have been implicated in the pathogenesis of various lung diseases, including chronic obstructive pulmonary disease (COPD). Such disturbances affect not only cellular energy metabolism but also alter a range of indispensable cellular homeostatic functions in which mitochondria are known to be involved. These range from cellular differentiation, cell death pathways, and cellular remodeling to physical barrier function and innate immunity, all of which are known to be impacted by exposure to cigarette smoke and have been linked to COPD pathogenesis. Next to their well-established role as the first physical frontline against external insults, lung epithelial cells are immunologically active. Malfunctioning epithelial cells with defective mitochondria are unable to maintain homeostasis and respond adequately to further stress or injury, which may ultimately shape the phenotype of lung diseases. In this review, we provide a comprehensive overview of the impact of cigarette smoke on the development of mitochondrial dysfunction in the lung epithelium and highlight the consequences for cell function, innate immune responses, epithelial remodeling, and epithelial barrier function in COPD. We also discuss the applicability and potential therapeutic value of recently proposed strategies for the restoration of mitochondrial function in the treatment of COPD.
    • Description of the novel planctomycetal genus Bremerella, containing Bremerella volcania sp. nov., isolated from an active volcanic site, and reclassification of Blastopirellula cremea as Bremerella cremea comb. nov.

      Rensink, Stephanie; Wiegand, Sandra; Kallscheuer, Nicolai; Rast, Patrick; Peeters, Stijn H; Heuer, Anja; Boedeker, Christian; Jetten, Mike S M; Rohde, Manfred; Jogler, Mareike; et al. (2020-01-01)
      Planctomycetes are part of the PVC superphylum together with Verrucomicrobia, Chlamydiae and others. They are budding bacteria with very distinctive characteristics, such as a remarkable morphology and cell biology. Planctomycetes can be found in almost all habitats, and seem to have a preference for marine biotic and abiotic surfaces, on which they frequently occur in biofilm-forming communities. To extend the number of axenic cultures of planctomycetal strains, we isolated Pan97T from a biofilm in a volcanic site close to the Italian island Panarea in the Thyrrhenian Sea. The physiology, genome and morphology of the novel strain were characterised revealing typical planctomycetal characteristics, such as, division by polar budding and presence of crateriform structures. The strain shows pear-shaped cells of 1.5 ± 0.3 µm × 0.8 ± 0.2 µm and forms white- to cream-coloured colonies on solid medium. Strain Pan97T is mesophilic and neutrophilic, since growth was observed  at a pH range of 5.5-9.5 with optimal growth at pH 7.0 and at a temperature range of 15-40 °C with a maximal growth rate at 36 °C. Pan97T has a genome size of 6,496,182 bp with a G + C content of 56.2%. 5264 protein-coding genes were identified, of which 2141 genes (41%) encode hypothetical proteins. Based on the phylogenetic analysis, we suggest that Pan97T (DSM 101992T = LMG 29460T) represents a novel species of a novel genus within the family Planctomycetaceae, for which we propose the name Bremerella gen. nov., with strain Pan97T classified as Bremerella volcania sp. nov. Based on our analysis, we also propose the reclassification of Blastopirellula cremea Lee et al. 2013 as Bremerella cremea comb. nov., as this species is considered to be the type species of the novel genus Bremerella.
    • Rhodopirellula heiligendammensis sp. nov., Rhodopirellula pilleata sp. nov., and Rhodopirellula solitaria sp. nov. isolated from natural or artificial marine surfaces in Northern Germany and California, USA, and emended description of the genus Rhodopirellula.

      Kallscheuer, Nicolai; Wiegand, Sandra; Jogler, Mareike; Boedeker, Christian; Peeters, Stijn H; Rast, Patrick; Heuer, Anja; Jetten, Mike S M; Rohde, Manfred; Jogler, Christian (2019-12-04)
      Expanding the collection of Planctomycetes by characterisation of novel species is key to better understanding of their complex lifestyles, uncommon cell biology and unexplored metabolism. Here, we isolated three novel planctomycetal strains from a kelp forest on the California Coastline at Monterey Bay or from plastic surfaces submerged in the Baltic Sea and the estuary of the river Warnow in the northeast of Germany. According to our phylogenetic analysis, the isolated strains Poly21T, Pla100T and CA85T represent three novel species within the genus Rhodopirellula. All three show typical planctomycetal traits such as division by budding. All are aerobic, mesophilic chemoheterotrophs and show genomic features comparable to other described Rhodopirellula species. However, strain CA85T is exceptional as it forms cream colonies, but no aggregates, which is a notable deviation from the pink- to red-pigmented and aggregate-forming Rhodopirellula species known thus far. We propose the names Rhodopirellula heiligendammensis sp. nov., Rhodopirellula pilleata sp. nov., and Rhodopirellula solitaria sp. nov. for the novel strains Poly21T (DSM 102266T = LMG 29467T = CECT 9847T = VKM B-3435T), Pla100T (DSM 102937T = LMG 29465T) and CA85T (DSM 109595T = LMG 29699T = VKM B-3451T), respectively, which we present as the respective type strains of these novel species.
    • Three marine strains constitute the novel genus and species Crateriforma conspicua in the phylum Planctomycetes.

      Peeters, Stijn H; Wiegand, Sandra; Kallscheuer, Nicolai; Jogler, Mareike; Heuer, Anja; Jetten, Mike S M; Rast, Patrick; Boedeker, Christian; Rohde, Manfred; Jogler, Christian (2020-01-01)
      Planctomycetes is a ubiquitous phylum of mostly aquatic bacteria that have a complex lifestyle and an unusual cell biology. Here, we describe three strains of the same novel genus and species isolated from three different environments; from a red biofilm at a hydrothermal vent in the Mediterranean Sea, from sediment in a salt-water fish tank, and from the surface of algae at the coast of the Balearic island Mallorca. The three strains Mal65T (DSM 100706T = LMG 29792T, Pan14r (DSM 29351 = LMG 29012), and V7 (DSM 29812 = CECT 9853 = VKM B-3427) show typical characteristics of the Planctomycetaceae family, such as cell division by budding, crateriform structures and growth in aggregates or rosettes.  The strains are mesophilic, neutrophilic to alkaliphilic as well as chemoheterotrophic and exhibit doubling times between 12 and 35 h. Based on our phylogenetic analysis, the three strains represent a single novel species of a new genus, for which we propose the name Crateriforma conspicua gen. nov. sp. nov.
    • Blastopirellula retiformator sp. nov. isolated from the shallow-sea hydrothermal vent system close to Panarea Island.

      Kallscheuer, Nicolai; Wiegand, Sandra; Heuer, Anja; Rensink, Stephanie; Boersma, Alje S; Jogler, Mareike; Boedeker, Christian; Peeters, Stijn H; Rast, Patrick; Jetten, Mike S M; et al. (2020-01-01)
      Aquatic bacteria belonging to the deep-branching phylum Planctomycetes play a major role in global carbon and nitrogen cycles. However, their uncommon morphology and physiology, and their roles and survival on biotic surfaces in marine environments, are only partially understood. Access to axenic cultures of different planctomycetal genera is key to study their complex lifestyles, uncommon cell biology and primary and secondary metabolism in more detail. Here, we describe the characterisation of strain Enr8T isolated from a marine biotic surface in the seawater close to the shallow-sea hydrothermal vent system off Panarea Island, an area with high temperature and pH gradients, and high availability of different sulphur and nitrogen sources resulting in a great microbial diversity. Strain Enr8T showed typical planctomycetal traits such as division by polar budding, aggregate formation and presence of fimbriae and crateriform structures. Growth was observed at ranges of 15-33 °C (optimum 30 °C), pH 6.0-8.0 (optimum 7.0) and at NaCl concentrations from 100 to 1200 mM (optimum 350-700 mM). Strain Enr8T forms white colonies on solid medium and white flakes in liquid culture. Its genome has a size of 6.20 Mb and a G + C content of 59.2%. Phylogenetically, the strain belongs to the genus Blastopirellula. We propose the name Blastopirellula retiformator sp. nov. for the novel species, represented by the type strain Enr8T (DSM 100415T = LMG 29081T).
    • Unsaturated Fatty Acids Control Biofilm Formation of Staphylococcus aureus and Other Gram-Positive Bacteria.

      Yuyama, Kamila Tomoko; Rohde, Manfred; Molinari, Gabriella; Stadler, Marc; Abraham, Wolf-Rainer (2020-11-08)
      Infections involving biofilms are difficult to treat due to increased resistances against antibiotics and the immune system. Hence, there is an urgent demand for novel drugs against biofilm infections. During our search for novel biofilm inhibitors from fungi, we isolated linoleic acid from the ascomycete Hypoxylon fragiforme which showed biofilm inhibition of several bacteria at sub-MIC concentrations. Many fatty acids possess antimicrobial activities, but their minimum inhibitory concentrations (MIC) are high and reports on biofilm interferences are scarce. We demonstrated that not only linoleic acid but several unsaturated long-chain fatty acids inhibited biofilms at sub-MIC concentrations. The antibiofilm activity exerted by long-chain fatty acids was mainly against Gram-positive bacteria, especially against Staphylococcus aureus. Micrographs of treated S. aureus biofilms revealed a reduction in the extracellular polymeric substances, pointing to a possible mode of action of fatty acids on S. aureus biofilms. The fatty acids had a strong species specificity. Poly-unsaturated fatty acids had higher activities than saturated ones, but no obvious rule could be found for the optimal length and desaturation for maximal activity. As free fatty acids are non-toxic and ubiquitous in food, they may offer a novel tool, especially in combination with antibiotics, for the control of biofilm infections.
    • Calycomorphotria hydatis gen. nov., sp. nov., a novel species in the family Planctomycetaceae with conspicuous subcellular structures.

      Schubert, Torsten; Kallscheuer, Nicolai; Wiegand, Sandra; Boedeker, Christian; Peeters, Stijn H; Jogler, Mareike; Heuer, Anja; Jetten, Mike S M; Rohde, Manfred; Jogler, Christian (2020-05-12)
      A novel strain belonging to the family Planctomycetaceae, designated V22T, was isolated from sediment of a seawater fish tank in Braunschweig, Germany. The isolate forms pink colonies on solid medium and displays common characteristics of planctomycetal strains, such as division by budding, formation of rosettes, a condensed nucleoid and presence of crateriform structures and fimbriae. Unusual invaginations of the cytoplasmic membrane and filamentous putative cytoskeletal elements were observed in thin sections analysed by transmission electron microscopy. Strain V22T is an aerobic heterotroph showing optimal growth at 30 °C and pH 8.5. During laboratory cultivations, strain V22T reached generation times of 10 h (maximal growth rate of 0.069 h-1). Its genome has a size of 5.2 Mb and a G + C content of 54.9%. Phylogenetically, the strain represents a novel genus and species in the family Planctomycetaceae, order Planctomycetales, class Planctomycetia. We propose the name Calycomorphotria hydatis gen. nov., sp. nov. for the novel taxon, represented by the type strain V22T (DSM 29767T = LMG 29080T).
    • Stereoselective Synthesis of a Protected Side Chain of Meliponamycin A.

      Andler, Oliver; Kazmaier, Uli; Organic Chemistry I, Saarland University, Campus Building C4.2, D-66123 Saarbrücken, GermanyHelmholtz Institute for Pharmaceutical Research Saarland (HIPS), Saarland University, Campus Building C8.1, D-66123 Saarbrücken, Germany (ACS/ American Chemical Society, 2023-03-28)
      The Matteson homologation was found to be a versatile tool for the construction of the linear polyketide side chain of meliponamycin and related compounds in only four steps. The ester dienolate version of this reaction allowed the introduction of the unsaturated ester moiety in a highly stereoselective fashion. Boronate oxidation/deoxygenation and Sharpless dihydroxylation are additional key steps in the stereoselective construction of this highly functionalized tetrahydropyran ring system, which is characteristic of this substance class
    • The assessment of childhood maltreatment and its associations with affective symptoms in adulthood: Results of the German National Cohort (NAKO).

      Klinger-König, Johanna; Streit, Fabian; Erhardt, Angelika; Kleineidam, Luca; Schmiedek, Florian; Schmidt, Börge; Investigators, Nako; Wagner, Michael; Deckert, Jürgen; Rietschel, Marcella; et al. (Taylor and Francis, 2022-03-18)
      Overall, 21,131 participants (27.5%) reported at least one type of childhood maltreatment; 14,017 participants (18.3%) reported exactly one type and 250 participants (0.3%) reported all five types of childhood maltreatment. Small differences regarding age (mean absolute deviation around the mean (MAD)=0.47), sex (MAD = 0.07) and education (MAD = 0.82) were observed. The severity of childhood maltreatment was associated with more severe symptoms of depression (β = 0.23), anxiety (β = 0.21) and perceived stress (β = 0.23) in adulthood, validated particularly for emotional abuse and emotional neglect.
    • Total In Vitro Biosynthesis of the Thioamitide Thioholgamide and Investigation of the Pathway.

      Sikandar, Asfandyar; Lopatniuk, Maria; Luzhetskyy, Andriy; Müller, Rolf; Koehnke, Jesko; Department of Microbial Natural Products (MINS), Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Center for Infection Research (HZI), Department of Pharmacy, Saarland University (UdS), Campus E8.1, Saarbrücken, 66123, GermanyDepartment of Pharmacy, Pharmaceutical Biotechnology, Saarland University, Saarbrücken, 66123, GermanyGerman Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Braunschweig, 38124, GermanyWorkgroup Structural Biology of Biosynthetic Enzymes, HIPS, HZI, UdS, Saarbrücken, 66123, GermanySchool of Chemistry, University of Glasgow, Glasgow, G12 8QQ, United Kingdom (ACS/ American Chemical Society, 2022-03-09)
      Thioholgamides are ribosomally synthesized and posttranslationally modified peptides (RiPPs), with potent activity against cancerous cell lines and an unprecedented structure. Despite being one of the most structurally and chemically complex RiPPs, very few biosynthetic steps have been elucidated. Here, we report the complete in vitro reconstitution of the biosynthetic pathway. We demonstrate that thioamidation is the first step and acts as a gatekeeper for downstream processing. Thr dehydration follows thioamidation, and our studies reveal that both these modifications require the formation of protein complexes─ThoH/I and ThoC/D. Harnessing the power of AlphaFold, we deduce that ThoD acts as a lyase and also proposes putative catalytic residues. ThoF catalyzes the oxidative decarboxylation of the terminal Cys, and the subsequent macrocyclization is facilitated by ThoE. This is followed by Ser dehydration, which is also carried out by ThoC/D. ThoG is responsible for histidine bis-N-methylation, which is a prerequisite for His β-hydroxylation─a modification carried out by ThoJ. The last step of the pathway is the removal of the leader peptide by ThoK to afford mature thioholgamide.
    • Optical Tweezers to Study RNA-Protein Interactions in Translation Regulation

      Pekarek, Lukas; Buck, Stefan; Caliskan, Neva; Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Zentrum für Infektionsforschung (Helmholtz Centre for Infection Research), Germany (JOVE, 2022-02-12)
      RNA adopts diverse structural folds, which are essential for its functions and thereby can impact diverse processes in the cell. In addition, the structure and function of an RNA can be modulated by various trans-acting factors, such as proteins, metabolites or other RNAs. Frameshifting RNA molecules, for instance, are regulatory RNAs located in coding regions, which direct translating ribosomes into an alternative open reading frame, and thereby act as gene switches. They may also adopt different folds after binding to proteins or other trans-factors. To dissect the role of RNA-binding proteins in translation and how they modulate RNA structure and stability, it is crucial to study the interplay and mechanical features of these RNA-protein complexes simultaneously. This work illustrates how to employ single-molecule-fluorescence-coupled optical tweezers to explore the conformational and thermodynamic landscape of RNA-protein complexes at a high resolution. As an example, the interaction of the SARS-CoV-2 programmed ribosomal frameshifting element with the trans-acting factor short isoform of zinc-finger antiviral protein is elaborated. In addition, fluorescence-labeled ribosomes were monitored using the confocal unit, which would ultimately enable the study of translation elongation. The fluorescence coupled OT assay can be widely applied to explore diverse RNA-protein complexes or trans-acting factors regulating translation and could facilitate studies of RNA-based gene regulation.