¹⁹F NMR Untersuchung des Konformationsaustauschs mehrerer Zustände im synthetischen Neomycin‐bindenden Riboschalter

Der synthetische Neomycin-bindende Riboschalter interagiert mit seinem Liganden Neomycin sowie mit den verwandten Antibiotika Ribostamycin und Paromomycin. Die Bindung dieser Aminoglykoside induziert sehr ähnliche Grundzustandsstrukturen in der RNA, allerdings kann nur Neomycin die Initiierung der Translation effizient unterdrücken. Der molekulare Ursprung dieser Unterschiede wurde auf Unterschiede in der Dynamik der Ligand-Riboschalter-Komplexe zurückgeführt. In diesem Artikel kombinieren wir fünf komplementäre fluorbasierte NMR-Methoden, um die Dynamik der drei Riboschalter-Komplexe im Sekunden- bis Mikrosekundenbereich genau zu quantifizieren. Unsere Daten offenbaren komplexe Austauschprozesse mit bis zu vier strukturell unterschiedlichen Zuständen. Wir interpretieren unsere Ergebnisse in einem Modell, das ein Zusammenspiel zwischen verschiedenen chemischen Gruppen in den Antibiotika und spezifischen Basen im Riboschalter zeigt. Allgemeiner unterstreichen unsere Daten das Potenzial von 19F NMR-Methoden, komplexe Austauschprozesse mit mehreren angeregten Zuständen zu charakterisieren

Multi‐Site Conformational Exchange in the Synthetic Neomycin‐Sensing Riboswitch Studied by 19 F NMR

The synthetic neomycin-sensing riboswitch interacts with its cognate ligand neomycin as well as with the related antibiotics ribostamycin and paromomycin. Binding of these aminoglycosides induces a very similar ground state structure in the RNA, however, only neomycin can efficiently repress translation initiation. The molecular origin of these differences has been traced back to differences in the dynamics of the ligand:riboswitch complexes. Here, we combine five complementary fluorine based NMR methods to accurately quantify seconds to microseconds dynamics in the three riboswitch complexes. Our data reveal complex exchange processes with up to four structurally different states. We interpret our findings in a model that shows an interplay between different chemical groups in the antibiotics and specific bases in the riboswitch. More generally, our data underscore the potential of 19F NMR methods to characterize complex exchange processes with multiple excited states

¹H, ¹³C and ¹⁵N and ³¹P chemical shift assignment for stem-loop 4 from the 5′-UTR of SARS-CoV-2

The SARS-CoV-2 virus is the cause of the respiratory disease COVID-19. As of today, therapeutic interventions in severe COVID-19 cases are still not available as no effective therapeutics have been developed so far. Despite the ongoing development of a number of effective vaccines, therapeutics to fight the disease once it has been contracted will still be required. Promising targets for the development of antiviral agents against SARS-CoV-2 can be found in the viral RNA genome. The 5′- and 3′-genomic ends of the 30 kb SCoV-2 genome are highly conserved among Betacoronaviruses and contain structured RNA elements involved in the translation and replication of the viral genome. The 40 nucleotides (nt) long highly conserved stem-loop 4 (5_SL4) is located within the 5′-untranslated region (5′-UTR) important for viral replication. 5_SL4 features an extended stem structure disrupted by several pyrimidine mismatches and is capped by a pentaloop. Here, we report extensive ¹H, ¹³C and ¹⁵N and ³¹P resonance assignments of 5_SL4 as the basis for in-depth structural and ligand screening studies by solution NMR spectroscopy

“What am I going to say here?” The experiences of doctors and nurses communicating with patients in a cancer unit.

This paper describes a study investigating the provider-patient communication perceptions, experiences, needs and strategies of doctors and nurses working together in a UK cancer setting. This was a qualitative study using individual interviews and 32 focus group discussions. Interpretative Phenomenological analysis (IPA) was used to underpin data collection and analysis. Twenty-six staff participated in the project (18 nurses and 8 doctors). Both professional groups identified an inherent emotional strain in their daily interactions with patients. The strategies they adopted to reduce this strain fell into two main categories: 1) Handling or managing the patient to keep negative emotion at bay; and 2) Managing self to keep negative emotion at bay. These strategies allowed staff to maintain a sense of control in an emotionally-stressful environment. Most believed that their communication skills were sufficient. In conclusion, communicating with and caring for cancer patients causes considerable psycho-social burden for doctors and nurses. Managing this burden influences their communication with patients. Without recognition of the need for staff to protect their own emotional well-being, communication skills training programmes, emphasised in current UK cancer care guidelines, may have little impact on practice

NMR assignment of non-modified tRNAIle from Escherichia coli

tRNAs are L-shaped RNA molecules of ~ 80 nucleotides that are responsible for decoding the mRNA and for the incorporation of the correct amino acid into the growing peptidyl-chain at the ribosome. They occur in all kingdoms of life and both their functions, and their structure are highly conserved. The L-shaped tertiary structure is based on a cloverleaf-like secondary structure that consists of four base paired stems connected by three to four loops. The anticodon base triplet, which is complementary to the sequence of the mRNA, resides in the anticodon loop whereas the amino acid is attached to the sequence CCA at the 3′-terminus of the molecule. tRNAs exhibit very stable secondary and tertiary structures and contain up to 10% modified nucleotides. However, their structure and function can also be maintained in the absence of nucleotide modifications. Here, we present the assignments of nucleobase resonances of the non-modified 77 nt tRNAIle from the gram-negative bacterium Escherichia coli. We obtained assignments for all imino resonances visible in the spectra of the tRNA as well as for additional exchangeable and non-exchangeable protons and for heteronuclei of the nucleobases. Based on these assignments we could determine the chemical shift differences between modified and non-modified tRNAIle as a first step towards the analysis of the effect of nucleotide modifications on tRNA’s structure and dynamics

An intricate balance of hydrogen bonding, ion atmosphere and dynamics facilitates a seamless uracil to cytosine substitution in the U-turn of the neomycin-sensing riboswitch

The neomycin sensing riboswitch is the smallest biologically functional RNA riboswitch, forming a hairpin capped with a U-turn loop—a well-known RNA motif containing a conserved uracil. It was shown previously that a U→C substitution of the eponymous conserved uracil does not alter the riboswitch structure due to C protonation at N3. Furthermore, cytosine is evolutionary permitted to replace uracil in other U-turns. Here, we use molecular dynamics simulations to study the molecular basis of this substitution in the neomycin sensing riboswitch and show that a structure-stabilizing monovalent cation-binding site in the wild-type RNA is the main reason for its negligible structural effect. We then use NMR spectroscopy to confirm the existence of this cation-binding site and to demonstrate its effects on RNA stability. Lastly, using quantum chemical calculations, we show that the cation-binding site is altering the electronic environment of the wild-type U-turn so that it is more similar to the cytosine mutant. The study reveals an amazingly complex and delicate interplay between various energy contributions shaping up the 3D structure and evolution of nucleic acids

High-resolution structure of stem-loop 4 from the 5′-UTR of SARS-CoV-2 solved by solution state NMR

We present the high-resolution structure of stem-loop 4 of the 5′-untranslated region (5_SL4) of the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) genome solved by solution state nuclear magnetic resonance spectroscopy. 5_SL4 adopts an extended rod-like structure with a single flexible looped-out nucleotide and two mixed tandem mismatches, each composed of a G•U wobble base pair and a pyrimidine•pyrimidine mismatch, which are incorporated into the stem-loop structure. Both the tandem mismatches and the looped-out residue destabilize the stem-loop structure locally. Their distribution along the 5_SL4 stem-loop suggests a role of these non-canonical elements in retaining functionally important structural plasticity in particular with regard to the accessibility of the start codon of an upstream open reading frame located in the RNA's apical loop. The apical loop—although mostly flexible—harbors residual structural features suggesting an additional role in molecular recognition processes. 5_SL4 is highly conserved among the different variants of SARS-CoV-2 and can be targeted by small molecule ligands, which it binds with intermediate affinity in the vicinity of the non-canonical elements within the stem-loop structure

Polypharmacy in chronic diseases–Reduction of Inappropriate Medication and Adverse drug events in older populations by electronic Decision Support (PRIMA-eDS): study protocol for a randomized controlled trial

Background: Multimorbidity is increasing in aging populations with a corresponding increase in polypharmacy as well as inappropriate prescribing. Depending on definitions, 25-50 % of patients aged 75 years or older are exposed to at least five drugs. Evidence is increasing that polypharmacy, even when guidelines advise the prescribing of each drug individually, can potentially cause more harm than benefit to older patients, due to factors such as drug-drug and drug-disease interactions. Several approaches reducing polypharmacy and inappropriate prescribing have been proposed, but evidence showing a benefit of these measures regarding clinically relevant endpoints is scarce. There is an urgent need to implement more effective strategies. We therefore set out to develop an evidence-based electronic decision support (eDS) tool to aid physicians in reducing inappropriate prescribing and test its effectiveness in a large-scale cluster-randomized controlled trial.Methods: The “Polypharmacy in chronic diseases–Reduction of Inappropriate Medication and Adverse drug events in older populations” (PRIMA)-eDS tool is a tool comprising an indication check and recommendations for the reduction of polypharmacy and inappropriate prescribing based on systematic reviews and guidelines, the European list of inappropriate medications for older people, the SFINX-database of interactions, the PHARAO-database on adverse effects, and the RENBASE-database on renal dosing. The tool will be evaluated in a cluster-randomized controlled trial involving 325 general practitioners (GPs) and around 3500 patients across five study centres in the United Kingdom, Germany, Austria and Italy. GP practices will be asked to recruit 11 patients aged 75 years or older who are taking at least eight medications and will be cluster-randomized after completion of patient recruitment. Intervention GPs will have access to the PRIMA-eDS tool, while control GPs will treat their patients according to current guidelines (usual care) without access to the PRIMA-eDS tool. After an observation time of 2 years, intervention and control groups will be compared regarding the primary composite endpoint of first non-elective hospitalization or death.Discussion: The principal hypothesis is that reduction of polypharmacy and inappropriate prescribing can improve the clinical composite outcome of hospitalization or death. A positive result of the trial will contribute substantially to the improvement of care in multimorbidity. The trial is necessary to investigate not only whether the reduction of polypharmacy improves outcome, but also whether GPs and patients are willing to follow the recommendations of the PRIMA-eDS tool.Trial registration: This trial has been registered with Current Controlled Trials Ltd. on 31 July 2014 ( ISRCTN10137559 )

Additional file 1: Figure S1. of Polypharmacy in chronic diseases–Reduction of Inappropriate Medication and Adverse drug events in older populations by electronic Decision Support (PRIMA-eDS): study protocol for a randomized controlled trial

Recruitment of 325 practices and 3575 patients for the PRIMA-eDS* trial. Figure describing the flow of recruitment for the PRIMA-eDS trial. (JPG 117 kb