TY - JOUR A1 - Dunce, James M. A1 - Milburn, Amy E. A1 - Gurusaran, Manickam A1 - da Cruz, Irene A1 - Sen, Lee T. A1 - Benavente, Ricardo A1 - Davies, Owen R. T1 - Structural basis of meiotic telomere attachment to the nuclear envelope by MAJIN-TERB2-TERB1 JF - Nature Communications N2 - Meiotic chromosomes undergo rapid prophase movements, which are thought to facilitate the formation of inter-homologue recombination intermediates that underlie synapsis, crossing over and segregation. The meiotic telomere complex (MAJIN, TERB1, TERB2) tethers telomere ends to the nuclear envelope and transmits cytoskeletal forces via the LINC complex to drive these rapid movements. Here, we report the molecular architecture of the meiotic telomere complex through the crystal structure of MAJIN-TERB2, together with light and X-ray scattering studies of wider complexes. The MAJIN-TERB2 2:2 hetero-tetramer binds strongly to DNA and is tethered through long flexible linkers to the inner nuclear membrane and two TRF1-binding 1:1 TERB2-TERB1 complexes. Our complementary structured illumination microscopy studies and biochemical findings reveal a telomere attachment mechanism in which MAJIN-TERB2-TERB1 recruits telomere-bound TRF1, which is then displaced during pachytene, allowing MAJIN-TERB2-TERB1 to bind telomeric DNA and form a mature attachment plate. KW - DNA KW - meiosis KW - proteins KW - super-resolution microscopy KW - X-ray crystallography Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-226416 VL - 9 ER - TY - JOUR A1 - Bencurova, Elena A1 - Akash, Aman A1 - Dobson, Renwick C.J. A1 - Dandekar, Thomas T1 - DNA storage-from natural biology to synthetic biology JF - Computational and Structural Biotechnology Journal N2 - Natural DNA storage allows cellular differentiation, evolution, the growth of our children and controls all our ecosystems. Here, we discuss the fundamental aspects of DNA storage and recent advances in this field, with special emphasis on natural processes and solutions that can be exploited. We point out new ways of efficient DNA and nucleotide storage that are inspired by nature. Within a few years DNA-based information storage may become an attractive and natural complementation to current electronic data storage systems. We discuss rapid and directed access (e.g. DNA elements such as promotors, enhancers), regulatory signals and modulation (e.g. lncRNA) as well as integrated high-density storage and processing modules (e.g. chromosomal territories). There is pragmatic DNA storage for use in biotechnology and human genetics. We examine DNA storage as an approach for synthetic biology (e.g. light-controlled nucleotide processing enzymes). The natural polymers of DNA and RNA offer much for direct storage operations (read-in, read-out, access control). The inbuilt parallelism (many molecules at many places working at the same time) is important for fast processing of information. Using biology concepts from chromosomal storage, nucleic acid processing as well as polymer material sciences such as electronical effects in enzymes, graphene, nanocellulose up to DNA macramé , DNA wires and DNA-based aptamer field effect transistors will open up new applications gradually replacing classical information storage methods in ever more areas over time (decades). KW - DNA KW - RNA KW - data storage KW - natural processing KW - synthetic biology Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-349971 SN - 2001-0370 VL - 21 ER - TY - THES A1 - Neitz, Hermann T1 - Hydrophobic recognition motifs in functionalized DNA T1 - Hydrophobe Erkennungsmotive in funktionalisierter DNA N2 - In wässriger Umgebung spielen hydrophobe Wechselwirkungen eine wichtige Rolle für die DNA. Die Einführung von Modifikationen, die auf hydrophoben aromatischen Einheiten basieren, kann die Erkennung und Reaktivität von funktionellen Gruppen in der DNA steuern. Modifikationen können durch ein künstliches Rückgrat oder in Form einer Erweiterung der Nukleobasen eingebracht werden und so zu zusätzlichen Eigenschaften der DNA führen. Diese Dissertation befasst sich mit der Verwendung von hydrophoben Einheiten zur Funktionalisierung von DNA. Im ersten Teil der Arbeit wurde das Tolanmotiv (Diphenylacetylen) in Kombination mit dem acyclischen Rückgrat von GNA und BuNA verwendet, um Erkennungseinheiten im DNA-Kontext zu erzeugen. Die gezielte Fluorierung der aromatischen Ringe des Tolan-Bausteins bildete die Grundlage für eine supramolekulare Sprache, die auf Aren-Fluoroaren-Wechselwirkungen basiert. Die spezifische Erkennung wurde mittels thermodynamischer, kinetischer und NMR-spektroskopischer Methoden untersucht. Im zweiten Teil der Arbeit wurden Desoxyuridin-Derivate mit einer hydrophoben aromatischen Modifikation hergestellt und in die DNA-Doppelhelix eingebaut. Die Bestrahlung mit UV-Licht führte zu einer [2+2]-Cycloaddition zwischen zwei modifizierten Nukleosiden in der DNA. Das Reaktionsprodukt wurde strukturell charakterisiert und die Reaktion in verschiedenen biochemischen und nanotechnologischen DNA-Anwendungen eingesetzt. N2 - In aqueous environment, hydrophobic interactions play an important role for DNA. The introduction of modifications based on hydrophobic aromatic moieties offers additional ways for controlling recognition and reactivity of functional groups in DNA. Modifications are introduced through an artificial backbone or in the form of an extension of the nucleobases, resulting in additional properties of the DNA. This dissertation focuses on the use of hydrophobic units for the functionalization of DNA. In the first part of the work, the tolane (i. e. diphenylacetylene) motif was used in combination with the acyclic backbone of GNA and BuNA to generate recognition units in the DNA context. Fluorination of the aromatic rings in the tolane moiety provided the basis for a supramolecular language based on arene-fluoroarene interactions. The specific recognition was investigated by thermodynamic, kinetic and NMR spectroscopic methods. In the second part of the work, deoxyuridine derivatives with a hydrophobic aromatic modification were prepared and incorporated into DNA duplexes. The irradiation with UV light led to a [2+2] cycloaddition reaction between two modified nucleosides in the DNA. This reaction product was structurally characterized and the reaction was used in various biochemical and nanotechnological DNA applications. KW - Supramolekulare Chemie KW - Arene-Fluoroarene KW - Artificial Base Pair KW - Supramolecular Interaction KW - XNA KW - Crosslinking KW - DNA KW - DNS Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-348382 ER - TY - JOUR A1 - Neitz, Hermann A1 - Bessi, Irene A1 - Kachler, Valentin A1 - Michel, Manuela A1 - Höbartner, Claudia T1 - Tailored tolane‐perfluorotolane assembly as supramolecular base pair replacement in DNA JF - Angewandte Chemie International Edition N2 - Arene‐fluoroarene interactions offer outstanding possibilities for engineering of supramolecular systems, including nucleic acids. Here, we implement the tolane‐perfluorotolane interaction as base pair replacement in DNA. Tolane (THH) and perfluorotolane (TFF) moieties were connected to acyclic backbone units, comprising glycol nucleic acid (GNA) or butyl nucleic acid (BuNA) building blocks, that were incorporated via phosphoramidite chemistry at opposite positions in a DNA duplex. Thermodynamic analyses by UV thermal melting revealed a compelling stabilization by THH/TFF heteropairs only when connected to the BuNA backbone, but not with the shorter GNA linker. Detailed NMR studies confirmed the preference of the BuNA backbone for enhanced polar π‐stacking. This work defines how orthogonal supramolecular interactions can be tailored by small constitutional changes in the DNA backbone, and it inspires future studies of arene‐fluoroarene‐programmed assembly of DNA. KW - arene-fluoroarene KW - artificial base pair KW - DNA KW - sSupramolecular interaction KW - XNA Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-312575 VL - 62 IS - 1 ER - TY - JOUR A1 - Aydinli, Muharrem A1 - Liang, Chunguang A1 - Dandekar, Thomas T1 - Motif and conserved module analysis in DNA (promoters, enhancers) and RNA (lncRNA, mRNA) using AlModules JF - Scientific Reports N2 - Nucleic acid motifs consist of conserved and variable nucleotide regions. For functional action, several motifs are combined to modules. The tool AIModules allows identification of such motifs including combinations of them and conservation in several nucleic acid stretches. AIModules recognizes conserved motifs and combinations of motifs (modules) allowing a number of interesting biological applications such as analysis of promoter and transcription factor binding sites (TFBS), identification of conserved modules shared between several gene families, e.g. promoter regions, but also analysis of shared and conserved other DNA motifs such as enhancers and silencers, in mRNA (motifs or regulatory elements e.g. for polyadenylation) and lncRNAs. The tool AIModules presented here is an integrated solution for motif analysis, offered as a Web service as well as downloadable software. Several nucleotide sequences are queried for TFBSs using predefined matrices from the JASPAR DB or by using one’s own matrices for diverse types of DNA or RNA motif discovery. Furthermore, AIModules can find TFBSs common to two or more sequences. Demanding high or low conservation, AIModules outperforms other solutions in speed and finds more modules (specific combinations of TFBS) than alternative available software. The application also searches RNA motifs such as polyadenylation site or RNA–protein binding motifs as well as DNA motifs such as enhancers as well as user-specified motif combinations (https://bioinfo-wuerz.de/aimodules/; alternative entry pages: https://aimodules.heinzelab.de or https://www.biozentrum.uni-wuerzburg.de/bioinfo/computing/aimodules). The application is free and open source whether used online, on-site, or locally. KW - AIModules KW - nucleic acid motifs KW - DNA Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-301268 VL - 12 IS - 1 ER - TY - JOUR A1 - Sanyal, Anirban A1 - Wallaschek, Nina A1 - Glass, Mandy A1 - Flamand, Louis A1 - Wight, Darren J. A1 - Kaufer, Benedikt B. T1 - The ND10 Complex Represses Lytic Human Herpesvirus 6A Replication and Promotes Silencing of the Viral Genome JF - Viruses N2 - Human herpesvirus 6A (HHV-6A) replicates in peripheral blood mononuclear cells (PBMCs) and various T-cell lines in vitro. Intriguingly, the virus can also establish latency in these cells, but it remains unknown what influences the decision between lytic replication and the latency of the virus. Incoming virus genomes are confronted with the nuclear domain 10 (ND10) complex as part of an intrinsic antiviral response. Most herpesviruses can efficiently subvert ND10, but its role in HHV-6A infection remains poorly understood. In this study, we investigated if the ND10 complex affects HHV-6A replication and contributes to the silencing of the virus genome during latency. We could demonstrate that ND10 complex was not dissociated upon infection, while the number of ND10 bodies was reduced in lytically infected cells. Virus replication was significantly enhanced upon knock down of the ND10 complex using shRNAs against its major constituents promyelocytic leukemia protein (PML), hDaxx, and Sp100. In addition, we could demonstrate that viral genes are more efficiently silenced in the presence of a functional ND10 complex. Our data thereby provides the first evidence that the cellular ND10 complex plays an important role in suppressing HHV-6A lytic replication and the silencing of the virus genome in latently infected cells. KW - human herpesvirus 6 KW - ND10 complex KW - PML KW - lytic replication KW - latency KW - PML nuclear-bodies KW - gene-expression KW - virus-infection KW - in-vitro KW - DNA Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-227337 VL - 10 IS - 8 ER - TY - THES A1 - Höflein, Felix T1 - Kinetik der Schistosomen-spezifischen DNA nach Behandlung mit Praziquantel und Bestimmung der Schistosomiasis-Prävalenz einer in einem Nicht-Endemiegebiet lebenden Risikopopulation sowie der Evaluation ausgewählter diagnostischer Verfahren T1 - Kinetics of schistosoma-specific DNA after treatment with praziquantel and determination of the schistosomiasis prevalence in a risk population living in a non-endemic area and the evaluation of selected diagnostic methods N2 - In dieser Arbeit wurden Bewohner/-innen der Würzburger Gemeinschaftsunterkünfte für Geflüchtete auf das Vorliegen einer Schistosomiasis gescreent. Lag eine behandlungsdürftige Infektion vor, wurden die Teilnehmenden mit Praziquantel behandelt, um im nachfolgenden Verlauf freiwillig an der Erstellung einer Schistosomen-DNA-Kinetik mitzuwirken. Eine Besonderheit der Studie lag dabei in der fehlenden Möglichkeit einer Reinfektion, da sich die Betroffenen während des Follow-ups in einem Endemie-freien Gebiet aufhielten. Für das Screening kamen ein CCA-Urin-Schnelltest sowie ein ICT zum Einsatz. Die Diagnosesicherung wurde durch die Mikroskopie oder die qPCR angestrebt. Es zeigte sich, dass die Kombination von CCA-Test und ICT einen positiven prädiktiven Wert von 80 % für das tatsächliche Vorliegen einer Schistosomen-Infektion liefert. Die Schistosomiasis-Prävalenz der hier untersuchten, in einem Nicht-Endemiegebiet lebenden Risikopopulation, wurde auf 3,9 % bestimmt und ist im Vergleich zu bisherigen Veröffentlichungen als niedrig anzusehen. Dabei ist zu beachten, dass die Prävalenz zum Teil deutlich überschätzt werden kann, sofern der CCA-Urin-Schnelltest als alleiniges Diagnosekriterium eingesetzt wird (PrävalenzCCA = 27,6 %). Die Erstellung der DNA-Kinetik mittels qPCR zeigte, dass die Behandlung mit Praziquantel einen nach 3 Tagen messbaren, signifikanten (p < 0,05) Anstieg der DNA-Konzentration im Serum zur Folge hatte, welcher im weiteren Verlauf kontinuierlich abfiel. Im Mittel wurde nach 48 Tagen der Schwellenwert der DNA-Konzentration unterschritten, der ohne vorausgegangene Behandlung als positiv und therapiebedürftig gewertet worden wäre. Durch Inter- und Extrapolation der gewonnen Daten, konnte eine Funktion errechnet werden, die den zeitlichen Verlauf des Zerfalls der Schistosomen-DNA beschreibt und somit zur Ermittlung weiterer Therapie- und Kontrollmöglichkeit der Schistosomiasis beitragen kann. N2 - Residents of the Würzburg communal accommodation for refugees were screened for the presence of schistosomiasis. If an infection requiring treatment was present, the participants were treated with praziquantel. After the intervention several serum samples were taken to determine schistosoma DNA kinetics. A special feature of the study was the lack of possibility of reinfection, since those affected stayed in an non-endemic area during the follow-up. A rapid CCA urine test and an ICT were used for the screening. The diagnosis was confirmed by microscopy or qPCR. It was shown that the combination of CCA test and ICT provides a positive predictive value of 80% for the actual presence of schistosoma infection. The schistosomiasis prevalence of the risk population was determined at 3.9% and can be regarded as low compared to previous publications. It should be noted that the prevalence can in some cases be significantly overestimated if the rapid CCA urine test is used as the single diagnostic criteria (CCA prevalence = 27.6%). The determination of the DNA kinetics using qPCR showed that the treatment with praziquantel resulted in a measurable, significant (p < 0.05) increase in the DNA concentration in the serum after 3 days, which continued to decrease over time. On average, after 48 days the DNA concentration had fallen below the threshold value that would have detected a treatment requiring infection. By interpolating and extrapolating the data, a function that describes the the decay of the schistosoma DNA over time was calculated and can therefor contribute to the determination of further therapy and control of schistosomiasis. KW - Schistosomiasis KW - DNA KW - Kinetik KW - Prävalenz KW - Gemeinschaftsunterkunft KW - Kinetics KW - Prevalence Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-297909 ER - TY - THES A1 - Siewert, Aaron T1 - Nucleotide analogs as rigid spin labels for DNA and RNA T1 - Nukleotidanaloga als starre Spinmarker für DNA und RNA N2 - Nucleic acids are one of the important classes of biomolecules together with carbohydrates, proteins and lipids. Both deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are most well known for their respective roles in the storage and expression of genetic information. Over the course of the last decades, nucleic acids with a variety of other functions have been discovered in biological organisms or created artificially. Examples of these functional nucleic acids are riboswitches, aptamers and ribozymes. In order to gain information regarding their function, several analytical methods can be used. Electron paramagnetic resonance (EPR) spectroscopy is one of several techniques which can be used to study nucleic acid structure and dynamics. However, EPR spectroscopy requires unpaired electrons and because nucleic acids themselves are not paramagnetic, the incorporation of spin labels which carry a radical is necessary. Here, three new spin labels for the analysis of nucleic acids by EPR spectroscopy are presented. All of them share two important design features. First, the paramagnetic center is located at a nitroxide, flanked by ethyl groups to prevent nitroxide degradation, for example during solid phase synthesis. Furthermore, they were designed with rigidity as an important quality, in order to be useful for applications like pulsed electron double resonance (PELDOR) spectroscopy, where independent motion of the spin labels relative to the macromolecule has a noticeable negative effect on the precision of the measurements. Benzi-spin is a spin label which differs from most previous examples of rigid spin labels in that rather than being based on a canonical nucleoside, with a specific base pairing partner, it is supposed to be a universal nucleoside which is sufficiently rigid for EPR measurements when placed opposite to a number of different nucleosides. Benzi-spin was successfully incorporated into a 20 nt oligonucleotide and its base pairing behavior with seven different nucleosides was examined by UV/VIS thermal denaturation and continuous wave (CW) EPR experiments. The results show only minor differences between the different nucleosides, thus confirming the ability of benzi-spin to act as a universally applicable spin label. Lumi-spin is derived from lumichrome. It features a rigid scaffold, as well as a free 2'-hydroxy group, which should make it well suited for PELDOR experiments once it is incorporated into RNA oligonucleotides. EÇr is based on the Ç family of spin labels, which contains the most well known rigid spin labels for nucleic acids to this day. It is essentially a version of EÇm with a free 2'-hydroxy group. It was converted to triphosphate EÇrTP and used for primer extension experiments to test the viability of enzymatic incorporation of rigid spin labels into oligonucleotides as an alternative to solid-phase synthesis. Incorporation into DNA by Therminator III DNA polymerase in both single-nucleotide and full-length primer extensions was achieved. All three of these spin labels represent further additions to the expanding toolbox of EPR spectroscopy on nucleic acids and might prove valuable for future research. N2 - Nukleinsäuren sind neben den Kohlenhydraten, Proteinen und Lipiden eine der wichtigen Klassen von Biomolekülen. Sowohl Deoxyribonukleinsäure (DNA) und Ribonukleinsäure (RNA) sind am besten für ihre Funktionen bei der Speicherung und Expression der genetischen Informationen bekannt. Während der letzten Jahrzehnte wurden Nukleinsäuren mit einer Vielzahl von Funktionen in biologischen Organismen entdeckt oder künstlich hergestellt. Beispiele für diese funktionellen Nukleinsäuren sind Riboswitches, Aptamere und Ribozyme. Um Informationen über ihre Funktionsweisen zu erhalten, können verschiedene analytische Methoden verwendet werden. Elektronenspinresonanzspektroscopie (ESR) ist eine Analysetechnik, die Aufschluss über Struktur und Dynamik von Nukleinsäuren geben kann. Für ESR Messungen werden ungepaarte Elektronen benötigt, sodass nicht paramagnetische Verbindungen mit einem Spinmarker modifiziert werden müssen, der ein Radikal trägt. In dieser Arbeit werden drei neue Spinmarker für die ESR Analyse von Nukleinsäuren vorgestellt. Allen liegen zwei Designprinzipien zugrunde. Erstens wird als paramagnetische Verbindung ein Nitroxid verwendet, welches von Ethylgruppen flankiert wird um das Radikal zu stabilisieren, zum Beispiel gegen Reagenzien, die in der Festphasensynthese verwendet werden. Zweitens sind die Nitroxide Teil starrer Ringsysteme. Dies ist besonders wichtig für Anwendungen wie Abstandsmessungen mittels Pulselektronendoppelresonanzspektroskopie (PELDOR), wo die Genauigkeit der Messung von Bewegungen der Spinmarker relativ zum Makromolekül beeinträchtigt wird. Benzi-spin unterscheidet sich von vielen anderen starren Spinmarkern dadurch, dass es nicht auf einem kanonischen Nukleosid mit einem spezifischen Bindungspartner basiert. Stattdessen handelt es sich um ein universelles Nukleosid, das unabhängig vom gegenüberliegenden Nukleosid starr genug für ESR Messungen ist. Benzi-spin wurde erfolgreich in ein Oligonucleotid eingebaut und seine Basenpaarung mit sieben verschiedenen Nukleosiden mittels UV/VIS Schmelzkurven und Continuous Wave (CW) ESR Experimenten untersucht. Die Ergebnisse zeigen nur geringe Unterschiede zwischen den verschiedenen Nukleosiden, was die Einsetzbarkeit von Benzi-spin als universeller Spinmarker bestätigt. Lumi-spin ist vom Lumichrom abgeleitet. Es zeichnet sich durch ein starres Gerüst und eine freie 2'-Hydroxygruppe aus, wodurch es gut für PELDOR Messungen in RNA geeignet sein sollte. EÇr gehört zur Ç Familie, welche die am besten bekannten starren Spinmarker für Nukleinsäuren enthält. Es handelt sich um eine Version von EÇm mit einer freien 2'-Hydroxygruppe. EÇr wurde zum Triphosphat EÇrTP konvertiert und für Primer Extension Experimente verwendet um die Möglichkeit des enzymatischen Einbaus starrer Spinmarker in Oligonukleotide als Alternative zur Festphasensynthese zu prüfen. Der Einbau in DNA mit Therminator III DNA Polymerase in Primer Extensions war erfolgreich. Alle drei Spinmarker erweitern die Möglichkeiten der ESR-spektroskopischen Untersuchung von Nukleinsäuren und können sich für zukünftige Forschung als nützlich erweisen. KW - Nucleinsäuren KW - DNS KW - RNS KW - Elektronenspinresonanzspektroskopie KW - Spin-Sonde KW - Nucleic acids KW - DNA KW - RNA KW - EPR spectroscopy KW - Spin labels Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-247657 ER - TY - INPR A1 - Wohlgemuth, Matthias A1 - Mitric, Roland T1 - Excitation energy transport in DNA modelled by multi-chromophoric field-induced surface hopping T2 - Physical Chemistry Chemical Physics N2 - Absorption of ultraviolet light is known as a major source of carcinogenic mutations of DNA. The underlying processes of excitation energy dissipation are yet not fully understood. In this work we provide a new and generally applicable route for studying the excitation energy transport in multi-chromophoric complexes at an atomistic level. The surface-hopping approach in the frame of the extended Frenkel exciton model combined with QM/MM techniques allowed us to simulate the photodynamics of the alternating (dAdT)10 : (dAdT)10 double-stranded DNA. In accordance with recent experiments, we find that the excited state decay is multiexponential, involving a long and a short component which are due to two distinct mechanisms: formation of long-lived delocalized excitonic and charge transfer states vs. ultrafast decaying localized states resembling those of the bare nucleobases. Our simulations explain all stages of the ultrafast photodynamics including initial photoexcitation, dynamical evolution out of the Franck-Condon region, excimer formation and nonradiative relaxation to the ground state. KW - Photodynamics KW - DNA Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-209467 ET - submitted version ER - TY - JOUR A1 - Reynolds, David L. A1 - Hofmeister, Brigitte T. A1 - Cliffe, Laura A1 - Siegel, T. Nicolai A1 - Andersson, Britta A. A1 - Beverley, Stephen M. A1 - Schmitz, Robert J. A1 - Sabatini, Robert T1 - Base J represses genes at the end of polycistronic gene clusters in Leishmania major by promoting RNAP II termination JF - Molecular Microbiology N2 - The genomes of kinetoplastids are organized into polycistronic gene clusters that are flanked by the modified DNA base J. Previous work has established a role of base J in promoting RNA polymerase II termination in Leishmania spp. where the loss of J leads to termination defects and transcription into adjacent gene clusters. It remains unclear whether these termination defects affect gene expression and whether read through transcription is detrimental to cell growth, thus explaining the essential nature of J. We now demonstrate that reduction of base J at specific sites within polycistronic gene clusters in L. major leads to read through transcription and increased expression of downstream genes in the cluster. Interestingly, subsequent transcription into the opposing polycistronic gene cluster does not lead to downregulation of sense mRNAs. These findings indicate a conserved role for J regulating transcription termination and expression of genes within polycistronic gene clusters in trypanosomatids. In contrast to the expectations often attributed to opposing transcription, the essential nature of J in Leishmania spp. is related to its role in gene repression rather than preventing transcriptional interference resulting from read through and dual strand transcription. KW - Trypanosoma-brucei KW - Transcription initiation KW - Messenger RNA KW - DNA KW - Genome KW - Cruzi KW - Hydroxymethyluracil KW - Expression KW - Parasite KW - Glucosyltransferase Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-187727 VL - 101 IS - 4 ER -