Micelle-Triggered b-Hairpin to a-Helix Transition in a 14-Residue Peptide from aBinding Choline- Repeat of the Pneumococcal Autolysin LytA

Choline-binding modules (CBMs) have a bb-solenoid structure composed of choline-binding repeats (CBR), which consist of a b-hairpin followed by a short linker. To find minimal peptides that are able to maintain the CBR native structure and to evaluate their remaining cholinebinding ability, we have analysed the third b-hairpin of the CBM from the pneumococcal LytA autolysin. Circular dichroism and NMR data reveal that this peptide forms a highly stable native-like b-hairpin both in aqueous solution and in the presence of trifluoroethanol, but, strikingly, the peptide structure is a stable amphipathic a-helix in both zwitterionic (dodecylphosphocholine) and anionic (sodium dodecylsulfate) detergent micelles, as well as in small unilamellar vesicles. This b-hairpin to a-helix conversion is reversible. Given that the b-hairpin and a-helix differ greatly in the distribution of hydrophobic and hydrophilic side chains, we propose that the amphipathicity is a requirement for a peptide structure to interact and to be stable in micelles or lipid vesicles. To our knowledge, this “chameleonic” behaviour is the only described case of a micelle-induced structural transition between two ordered peptide structures

DD04107-Derived neuronal exocytosis inhibitor peptides: Evidences for synaptotagmin-1 as a putative target

15 pags, 8 figs, 3 tabs. -- Supplementary data to this article can be found online at https://doi.org/10.1016/j.bioorg.2021.105231.The analgesic peptide DD04107 (Pal-EEMQRR-NH2) and its acetylated analogue inhibit α-calcitonin gene-related peptide (α-CGRP) exocytotic release from primary sensory neurons. Examining the crystal structure of the SNARE-Synaptotagmin-1(Syt1) complex, we hypothesized that these peptides could inhibit neuronal exocytosis by binding to Syt1, hampering at least partially its interaction with the SNARE complex. To address this hypothesis, we first interrogate the role of individual side-chains on the inhibition of α-CGRP release, finding that E1, M3, Q4 and R6 residues were crucial for activity. CD and NMR conformational analysis showed that linear peptides have tendency to adopt α-helical conformations, but the results with cyclic analogues indicated that this secondary structure is not needed for activity. Isothermal titration calorimetry (ITC) measurements demonstrate a direct interaction of some of these peptides with Syt1-C2B domain, but not with Syt7-C2B region, indicating selectivity. As expected for a compound able to inhibit α-CGRP release, cyclic peptide derivative Pal-E-cyclo[EMQK]R-NH2 showed potent in vivo analgesic activity, in a model of inflammatory pain. Molecular dynamics simulations provided a model consistent with KD values for the interaction of peptides with Syt1-C2B domain, and with their biological activity. Altogether, these results identify Syt1 as a potential new analgesic target.This work was supported by the Spanish Ministerio de Economía y Competitividad (MINECO-FEDER), RTI2018-097189-C2 and CTQ2017-84371-P), and the Spanish National Research Council (CSIC, 201880E109, 201980E030). The NMR experiments were performed in the “Manuel Rico” NMR laboratory, LMR, CSIC, a node of the Spanish Large-Scale National Facility ICTS R-LRB. We thank Prof. Josep Rizo and R. Voleti (Dept. Biophysics, Biochemistry and Pharmacology, UT Southwestern Medical Center, Dallas, USA) for providing the clones required for expressing Syt1 and Syt7 proteins. SG-R and AB belong to the Instituto de Investigación Sanitaria del Principado de Asturias (ISPA).Peer reviewe

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

The C-terminal Domains of Two Homologous Oleaceae β-1,3-Glucanases Recognize Carbohydrates Differently: Laminarin Binding by NMR

Ole e 9 and Fra e 9 are two allergenic β-1,3-glucanases from olive and ash tree pollens, respectively. Both proteins present a modular structure with a catalytic N-terminal domain and a carbohydrate-binding module (CBM) at the C-terminus. Despite their significant sequence resemblance, they differ in some functional properties, such as their catalytic activity and the carbohydrate-binding ability. Here, we have studied the different capability of the recombinant C-terminal domain of both allergens to bind laminarin by NMR titrations, binding assays and ultracentrifugation. We show that rCtD-Ole e 9 has a higher affinity for laminarin than rCtD-Fra e 9. The complexes have different exchange regimes on the NMR time scale in agreement with the different affinity for laminarin observed in the biochemical experiments. Utilizing NMR chemical shift perturbation data, we show that only one side of the protein surface is affected by the interaction and that the binding site is located in the inter-helical region between α1 and α2, which is buttressed by aromatic side chains. The binding surface is larger in rCtD-Ole e 9 which may account for its higher affinity for laminarin relative to rCtD-Fra e 9