Crenarchaeal CdvA Forms Double-Helical Filaments Containing DNA and Interacts with ESCRT-III-Like CdvB

International audienceBACKGROUND: The phylum Crenarchaeota lacks the FtsZ cell division hallmark of bacteria and employs instead Cdv proteins. While CdvB and CdvC are homologues of the eukaryotic ESCRT-III and Vps4 proteins, implicated in membrane fission processes during multivesicular body biogenesis, cytokinesis and budding of some enveloped viruses, little is known about the structure and function of CdvA. Here, we report the biochemical and biophysical characterization of the three Cdv proteins from the hyperthermophilic archaeon Metallospherae sedula. METHODOLOGY/PRINCIPAL FINDINGS: Using sucrose density gradient ultracentrifugation and negative staining electron microscopy, we evidenced for the first time that CdvA forms polymers in association with DNA, similar to known bacterial DNA partitioning proteins. We also observed that, in contrast to full-lengh CdvB that was purified as a monodisperse protein, the C-terminally deleted CdvB construct forms filamentous polymers, a phenomenon previously observed with eukaryotic ESCRT-III proteins. Based on size exclusion chromatography data combined with detection by multi-angle laser light scattering analysis, we demonstrated that CdvC assembles, in a nucleotide-independent way, as homopolymers resembling dodecamers and endowed with ATPase activity in vitro. The interactions between these putative cell division partners were further explored. Thus, besides confirming the previous observations that CdvB interacts with both CdvA and CdvC, our data demonstrate that CdvA/CdvB and CdvC/CdvB interactions are not mutually exclusive. CONCLUSIONS/SIGNIFICANCE: Our data reinforce the concept that Cdv proteins are closely related to the eukaryotic ESCRT-III counterparts and suggest that the organization of the ESCRT-III machinery at the Crenarchaeal cell division septum is organized by CdvA an ancient cytoskeleton protein that might help to coordinate genome segregation

Supporting Treatment decision making to Optimise the Prevention of STROKE in Atrial Fibrillation: The STOP STROKE in AF study. Protocol for a cluster randomised controlled trial

<p>Abstract</p> <p>Background</p> <p>Suboptimal uptake of anticoagulation for stroke prevention in atrial fibrillation has persisted for over 20 years, despite high-level evidence demonstrating its effectiveness in reducing the risk of fatal and disabling stroke.</p> <p>Methods</p> <p>The STOP STROKE in AF study is a national, cluster randomised controlled trial designed to improve the uptake of anticoagulation in primary care. General practitioners from around Australia enrolling in this ‘distance education’ program are mailed written educational materials, followed by an academic detailing session delivered via telephone by a medical peer, during which participants discuss patient de-identified cases. General practitioners are then randomised to receive written specialist feedback about the patient de-identified cases either before or after completing a three-month posttest audit. Specialist feedback is designed to provide participants with support and confidence to prescribe anticoagulation. The primary outcome is the proportion of patients with atrial fibrillation receiving oral anticoagulation at the time of the posttest audit.</p> <p>Discussion</p> <p>The STOP STROKE in AF study aims to evaluate a feasible intervention via distance education to prevent avoidable stroke due to atrial fibrillation. It provides a systematic test of augmenting academic detailing with expert feedback about patient management.</p> <p>Trial registration</p> <p>Australian Clinical Trials Registry Registration Number: ACTRN12611000076976.</p