Article

Type VI secretion requires a dynamic contractile phage tail-like structure.

Department of Microbiology and Immunobiology, Harvard Medical School, 200 Longwood Avenue, Boston, Massachusetts 02115, USA.
Nature (Impact Factor: 42.35). 03/2012; 483(7388):182-6. DOI: 10.1038/nature10846
Source: PubMed

ABSTRACT Type VI secretion systems are bacterial virulence-associated nanomachines composed of proteins that are evolutionarily related to components of bacteriophage tails. Here we show that protein secretion by the type VI secretion system of Vibrio cholerae requires the action of a dynamic intracellular tubular structure that is structurally and functionally homologous to contractile phage tail sheath. Time-lapse fluorescence light microscopy reveals that sheaths of the type VI secretion system cycle between assembly, quick contraction, disassembly and re-assembly. Whole-cell electron cryotomography further shows that the sheaths appear as long tubular structures in either extended or contracted conformations that are connected to the inner membrane by a distinct basal structure. These data support a model in which the contraction of the type VI secretion system sheath provides the energy needed to translocate proteins out of effector cells and into adjacent target cells.

0 Bookmarks
 · 
142 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Phylum Apicomplexa comprises a large group of obligate intracellular parasites of high medical and veterinary importance. These organisms succeed intracellularly by effecting remarkable changes in a broad range of diverse host cells. The transformation of the host erythrocyte is particularly striking in the case of the malaria parasite Plasmodium falciparum. P. falciparum exports hundreds of proteins that mediate a complex cellular renovation marked by changes in the permeability, rigidity, and cytoadherence properties of the host erythrocyte. The past decade has seen enormous progress in understanding the identity and function of these exported effectors, as well as the mechanisms by which they are trafficked into the host cell. Here we review these advances, place them in the context of host manipulation by related apicomplexans, and propose key directions for future research. Expected final online publication date for the Annual Review of Biochemistry Volume 84 is June 02, 2015. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
    Annual review of biochemistry. 01/2015;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Many of the new teaching methods that currently exist are based on collaborative learning. Indeed, cooperative work adds value to the processes of teaching and learning, allowing the acquisition of the Key Skills with greater ease and effectiveness. One of the fundamental factors to implement these methodologies based on cooperative work is the definition and formation of heterogeneous working groups among students. However, this is not a trivial task: the large number of parameters to be taken into account to generate heterogeneous groups in a class is a key parameter that increases the complexity of the task. Currently, this process of group allocation is manually solved by the teaching staff; an individual profile analysis is performed for each student and then each one is assigned to a particular group, which can take more than a week of work when the number of students is around 120. This paper presents a tool that supports the teaching staff in this daunting task and that allows the automatic generation of heterogeneous groups. The tool, its functionalities, the technical processes for development and the decisions to validate its design and obtain satisfactory results are detailed.
    2014 9th Iberian Conference on Information Systems and Technologies (CISTI); 06/2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: Burkholderia kururiensis M130 is one of the few rice endophytic diazotrophic bacteria identified thus far which is able to enhance growth of rice. To date, very little is known of how strain M130 and other endophytes enter and colonize plants. Here, we identified genes of strain M130 that are differentially regulated in the presence of rice plant extract. A genetic screening of a promoter probe transposon mutant genome bank and RNAseq analysis were performed. The screening of 10,100 insertions of the genomic transposon reporter library resulted in the isolation of 61 insertions displaying differential expression in response to rice macerate. The RNAseq results validated this screen and indicated that this endophytic bacterium undergoes major changes in the presence of plant extract regulating 27.7% of its open reading frames. A large number of differentially expressed genes encode membrane transporters and secretion systems, indicating that the exchange of molecules is an important aspect of bacterial endophytic growth. Genes related to motility, chemotaxis, and adhesion were also overrepresented, further suggesting plant-bacteria interaction. This work highlights the potential close signaling taking place between plants and bacteria and helps us to begin to understand the adaptation of an endophyte in planta.
    Molecular Plant-Microbe Interactions 01/2015; 28(1):10-21. · 4.46 Impact Factor

Preview

Download
4 Downloads
Available from