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

À Propos

International audienceCJUE 12 sept. 2013, n° C-64/12 et 18 juill. 2013, n° C-426/1

Regards : L'impact de la directive 2008/104 relative au travail intérimaire sur les droits nationaux

International audiencedeuxième parti

À Propos

International audienceCJUE 12 sept. 2013, n° C-64/12 et 18 juill. 2013, n° C-426/1

Phage therapy against antimicrobial resistance, design of the first clinical study Phagoburn.

peer reviewe

Diversity of <em>Acinetobacter baumannii</em> in Four French Military Hospitals, as Assessed by Multiple Locus Variable Number of Tandem Repeats Analysis

<div><h3>Background</h3><p>Infections by <em>A. calcoaceticus</em>-<em>A. baumannii</em> (ACB) complex isolates represent a serious threat for wounded and burn patients. Three international multidrug-resistant (MDR) clones (EU clone I-III) are responsible for a large proportion of nosocomial infections with <em>A. baumannii</em> but other emerging strains with high epidemic potential also occur.</p> <h3>Methodology/Principal Findings</h3><p>We automatized a Multiple locus variable number of tandem repeats (VNTR) analysis (MLVA) protocol and used it to investigate the genetic diversity of 136 ACB isolates from four military hospitals and one childrens hospital. <em>Acinetobacter</em> sp other than <em>baumannii</em> isolates represented 22.6% (31/137) with a majority being <em>A. pittii</em>. The genotyping protocol designed for <em>A.baumannii</em> was also efficient to cluster <em>A. pittii</em> isolates. Fifty-five percent of <em>A. baumannii</em> isolates belonged to the two international clones I and II, and we identified new clones which members were found in the different hospitals. Analysis of two CRISPR-cas systems helped define two clonal complexes and provided phylogenetic information to help trace back their emergence.</p> <h3>Conclusions/Significance</h3><p>The increasing occurrence of <em>A. baumannii</em> infections in the hospital calls for measures to rapidly characterize the isolates and identify emerging clones. The automatized MLVA protocol can be the instrument for such surveys. In addition, the investigation of CRISPR/cas systems may give important keys to understand the evolution of some highly successful clonal complexes.</p> </div

Polymorphism of the AYE CRISPR locus in <i>A. baumannii</i>.

<p>A) Schematic representation of the CRISPR locus in three sequenced genomes and at the growing end of isolates A28, P054 and P065. Arrows show the position of primers used to amplify a portion of the locus. Specific spacers are shown with grey boxes. B) Sequence of the growing end of strain AB307 and isolate A28. The sequence flanking the last DR is in italics.</p

Genetic diversity of 56 <i>A. baumannii</i> isolates.

<p>The legend is that of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0044597#pone-0044597-g001" target="_blank">Figure 1</a>.</p