A Review of Concussion Recognition, Assessment and Management for Paramedics

Although paramedics are trained in the recognition and management of traumatic brain injuries, the management of the patient with a concussion is a clinical presentation that may not be addressed in sufficient detail within paramedic education, and paramedics may be unaware of the latest evidence-based concussion treatment guidelines and recommendations. While life-support measures are rarely required in concussion injuries, it would be prudent for paramedics to familiarize themselves with this evolving area of concern in medicine. This brief overview aims to address these potential issues

Do paramedics have a role to play in organ donation?

The future role paramedics may play in organ donation is unclear, and potential ethical, legal and professional issues need to be thoroughly researched and addressed

The linker domain of the SNARE protein SNAP25 acts as a flexible molecular spacer that ensures efficient S-acylation

S-Acylation of the SNARE protein SNAP25 (synaptosomeassociated protein of 25 kDa) is mediated by a subset of Golgi zinc finger DHHC-type palmitoyltransferase (zDHHC) enzymes, particularly zDHHC17. The ankyrin repeat domain of zDHHC17 interacts with a short linear motif known as the zDHHC ankyrin repeat- binding motif (zDABM) in SNAP25 ( 112VVASQP 117), which is downstream of its S-acylated, cysteine-rich domain ( 85CGLCVCPC 92). Here, we investigated the importance of a flexible linker region (amino acids 93-111, referred to hereafter as the “mini-linker” region) that separates the zDABM and S-acylated cysteines in SNAP25. Shortening the mini-linker did not affect the SNAP25-zDHHC17 interaction but blocked S-acylation. Insertion of additional flexible glycine-serine repeats had no effect on S-acylation, but extended and rigid alanine-proline repeats perturbed it. A SNAP25 mutant in which the mini-linker region was substituted with a flexible glycine-serine linker of the same length underwent efficient S-acylation. Furthermore, this mutant displayed the same intracellular localization as WT SNAP25, indicating that the amino acid composition of the mini-linker is not important for SNAP25 localization. Using the results of previous peptide array experiments, we generated a SNAP25 mutant predicted to have a higher-affinity zDABM. This mutant interacted with zDHHC17 more strongly but was S-acylated with reduced efficiency in HEK293T cells, implying that a lower-affinity interaction of the SNAP25 zDABM with zDHHC17 is optimal for S-acylation efficiency. These results show that amino acids 93-111 in SNAP25 act as a flexible molecular spacer that ensures efficient coupling of the SNAP25-zDHHC17 interaction and S-acylation of SNAP25

Identification of key features required for efficient S-acylation and plasma membrane targeting of Sprouty-2

Sprouty-2 is an important regulator of growth factor signalling and a tumour suppressor protein. The defining feature of this protein is a cysteine-rich domain (CRD) that contains twenty-six cysteines and is modified by S-acylation. In this study, we show that the CRD of Sprouty-2 is differentially modified by S-acyltransferase enzymes. The high specificity/low activity zDHHC17 enzyme mediated restricted S-acylation of Sprouty-2, and cysteines-265/268 were identified as key targets of this enzyme. In contrast, the low specificity/high activity zDHHC3/zDHHC7 enzymes mediated more expansive modification of the Sprouty-2 CRD. Nevertheless, S-acylation by all enzymes enhanced Sprouty-2 expression, suggesting that S-acylation stabilises this protein. In addition, we identified two charged residues (aspartate-214 and lysine-223), present on opposite faces of a predicted alpha helix in the CRD, which are essential for S-acylation of Sprouty-2. Interestingly, mutations that perturbed S-acylation also led to a loss of plasma membrane localisation of Sprouty-2 in PC12 cells. This study provides insight into the mechanisms and outcomes of Sprouty-2 S-acylation, and highlights distinct patterns of S-acylation mediated by different classes of zDHHC enzymes

S-acylation of Sprouty and SPRED proteins by the S-acyltransferase zDHHC17 involves a novel mode of enzyme-substrate interaction

S-Acylation is an essential post-translational modification, which is mediated by a family of twenty-three zDHHC enzymes in humans. Several thousand proteins are modified by S-acylation; however, we lack a detailed understanding of how enzyme-substrate recognition and specificity is achieved. Previous work showed that the ankyrin repeat domain of zDHHC17 (ANK17) recognizes a short linear motif, known as the zDHHC ANK binding motif (zDABM) in substrate protein SNAP25, as a mechanism of substrate recruitment prior to S-acylation. Here, we investigated the S-acylation of the Sprouty and SPRED family of proteins by zDHHC17. Interestingly, although Sprouty-2 (Spry2) contains a zDABM that interacts with ANK17, this mode of binding is dispensable for S-acylation, and indeed removal of the zDABM does not completely ablate binding to zDHHC17. Furthermore, the related SPRED3 protein interacts with and is efficiently S-acylated by zDHHC17 despite lacking a zDABM. We undertook mutational analysis of SPRED3 to better understand the basis of its zDABM-independent interaction with zDHHC17. This analysis found that the cysteine-rich SPR domain of SPRED3, which is the defining feature of all Sprouty and SPRED proteins, interacts with zDHHC17. Surprisingly, the interaction with SPRED3 was independent of ANK17. Our mutational analysis of Spry2 was consistent with the SPR domain of this protein containing a zDHHC17 binding site, and Srpy2 also showed detectable binding to a zDHHC17 mutant lacking the ANK domain. Thus, zDHHC17 can recognize its substrates through ANK domain and zDABM-dependent and –independent mechanisms, and some substrates display more than one mode of binding to this enzyme

The endoplasmic reticulum-localized enzyme zDHHC6 mediates S-acylation of short transmembrane constructs from multiple type I and II membrane proteins

In this study, we investigated the S-acylation of two host cell proteins important for viral infection: TMPRSS2 (transmembrane serine protease 2), which cleaves SARS-CoV-2 spike to facilitate viral entry, and BST2 (Bone marrow stromal antigen 2), a general viral restriction factor. We found that both proteins were S-acylated by zDHHC6, an S-acyltransferase enzyme localized at the endoplasmic reticulum (ER), in co-expression experiments. Mutagenic analysis revealed that zDHHC6 modifies a single cysteine in each protein, which are in proximity to the transmembrane domains (TMDs). For TMPRSS2, the modified cysteine is positioned two residues into the TMD, whereas the modified cysteine in BST2 has a cytosolic location two amino acids upstream of the TMD. Cysteine swapping revealed that repositioning the target cysteine of TMPRSS2 further into the TMD substantially reduced S-acylation by zDHHC6. Interestingly, zDHHC6 efficiently S-acylated truncated forms of these proteins that contained only the TMDs and short juxtamembrane regions. The ability of zDHHC6 to modify short TMD sequences was also seen for the transferrin receptor (another type II membrane protein) and for five different type I membrane protein constructs, including CD4. Collectively, the results of this study show that zDHHC6 can modify diverse membrane proteins (Type I and II) and requires only the presence of the TMD and target cysteine for efficient S-acylation. Thus, zDHHC6 may be a broad specificity S-acyltransferase specialized for the modification of a diverse set of transmembrane proteins at the endoplasmic reticulum

Do paramedics have a role to play in organ donation? [Letter]

Batt, AM ORCiD: 0000-0001-6473-5397As readers are aware, many jurisdictions rely on paramedics to deliver ambulance services and emergency and urgent care, and as healthcare professionals, they have a duty of care to their patients. Does this duty of care include facilitating organ donation and patient’s wishes, if known or made known? Should paramedics play a role in identification and management of potential donors? Paramedics are not traditionally involved in organ donation, but in light of their changing role, it is not unreasonable to assume that they might well be in the near future

Inelastic Neutron Scattering Study of Pt II Complexes Displaying Anticancer Properties

International audienceThe well‐known platinum(II) chemotherapeutic drugs cisplatin [cis‐(NH3)2PtCl2] and carboplatin [Pt(NH3)2C6O4H6], as well as the analogous transplatin [trans‐(NH3)2PtCl2], were studied by inelastic neutron scattering (INS) spectroscopy, coupled to quantum mechanical methods, and some ancillary work with X‐ray diffraction on powders. An assignment of the experimental spectra was carried out based on the calculated INS transition frequencies and intensities (at the DFT level), thereby achieving a good correspondence between the calculated and observed data. Unusually good‐quality INS spectra were obtained from about 250 mg, which is the smallest sample of a hydrogenous compound for which a successful INS interpretation has been reported. The knowledge of the local configuration of this kind of complexes is essential for an accurate understanding of their activity, which will pave the way for the rational design of novel third‐generation drugs comprising cisplatin‐ and carboplatin‐like moieties

Development of a novel high-throughput screen for the identification of new inhibitors of protein S-acylation

Protein S-acylation is a reversible post-translational modification that modulates the localisation and function of many cellular proteins. S-acylation is mediated by a family of zinc finger DHHC domain-containing proteins encoded by 23 distinct ZDHHC genes in the human genome. These enzymes catalyse S-acylation in a two-step process involving “auto-acylation” of the cysteine residue in the catalytic DHHC motif followed by transfer of the acyl chain to a substrate cysteine. S-acylation is essential for many fundamental physiological processes, and there is growing interest in zDHHC enzymes as novel drug targets for a range of disorders. However, there is currently a lack of chemical modulators of S-acylation either for use as tool compounds or for potential development for therapeutic purposes. In this study, we developed and implemented a novel FRET-based high throughput assay for the discovery of compounds that interfere with auto-acylation of zDHHC2, an enzyme that is implicated in neuronal S-acylation pathways. A screen of >350,000 compounds identified two related tetrazole containing compounds (TTZ-1 and -2) that inhibited both zDHHC2 auto-acylation and substrate S-acylation in cell-free systems. Furthermore, these compounds were also active in HEK293T cells, where they inhibited the S-acylation of 2 substrates (SNAP25 and PSD95) mediated by different zDHHC enzymes, with some apparent isoform selectivity. Resynthesis of the hit compounds confirmed their activity, providing sufficient quantities of material for further investigations. The assays developed herein provide novel strategies to screen for zDHHC inhibitors, and the identified compounds add to the chemical toolbox for interrogating the cellular activities of zDHHC enzymes in S-acylation