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  • 1
    Publication Date: 2016-05-20
    Description: Several systems, including contractile tail bacteriophages, the type VI secretion system and R-type pyocins, use a multiprotein tubular apparatus to attach to and penetrate host cell membranes. This macromolecular machine resembles a stretched, coiled spring (or sheath) wound around a rigid tube with a spike-shaped protein at its tip. A baseplate structure, which is arguably the most complex part of this assembly, relays the contraction signal to the sheath. Here we present the atomic structure of the approximately 6-megadalton bacteriophage T4 baseplate in its pre- and post-host attachment states and explain the events that lead to sheath contraction in atomic detail. We establish the identity and function of a minimal set of components that is conserved in all contractile injection systems and show that the triggering mechanism is universally conserved.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Taylor, Nicholas M I -- Prokhorov, Nikolai S -- Guerrero-Ferreira, Ricardo C -- Shneider, Mikhail M -- Browning, Christopher -- Goldie, Kenneth N -- Stahlberg, Henning -- Leiman, Petr G -- England -- Nature. 2016 May 18;533(7603):346-52. doi: 10.1038/nature17971.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Ecole Polytechnique Federale de Lausanne (EPFL), BSP-415, 1015 Lausanne, Switzerland. ; Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, pr. 60-letiya Oktyabrya, 7 build. 2, 117312, Moscow, Russia. ; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Laboratory of Molecular Bioengineering, 16/10 Miklukho-Maklaya St., 117997 Moscow, Russia. ; Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Mattenstrasse 26, 4058 Basel, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27193680" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2013-08-09
    Description: The bacterial type VI secretion system (T6SS) is a large multicomponent, dynamic macromolecular machine that has an important role in the ecology of many Gram-negative bacteria. T6SS is responsible for translocation of a wide range of toxic effector molecules, allowing predatory cells to kill both prokaryotic as well as eukaryotic prey cells. The T6SS organelle is functionally analogous to contractile tails of bacteriophages and is thought to attack cells by initially penetrating them with a trimeric protein complex called the VgrG spike. Neither the exact protein composition of the T6SS organelle nor the mechanisms of effector selection and delivery are known. Here we report that proteins from the PAAR (proline-alanine-alanine-arginine) repeat superfamily form a sharp conical extension on the VgrG spike, which is further involved in attaching effector domains to the spike. The crystal structures of two PAAR-repeat proteins bound to VgrG-like partners show that these proteins sharpen the tip of the T6SS spike complex. We demonstrate that PAAR proteins are essential for T6SS-mediated secretion and target cell killing by Vibrio cholerae and Acinetobacter baylyi. Our results indicate a new model of the T6SS organelle in which the VgrG-PAAR spike complex is decorated with multiple effectors that are delivered simultaneously into target cells in a single contraction-driven translocation event.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3792578/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3792578/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shneider, Mikhail M -- Buth, Sergey A -- Ho, Brian T -- Basler, Marek -- Mekalanos, John J -- Leiman, Petr G -- AI-01845/AI/NIAID NIH HHS/ -- AI-026289/AI/NIAID NIH HHS/ -- R01 AI018045/AI/NIAID NIH HHS/ -- R01 AI026289/AI/NIAID NIH HHS/ -- England -- Nature. 2013 Aug 15;500(7462):350-3. doi: 10.1038/nature12453. Epub 2013 Aug 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Ecole Polytechnique Federale de Lausanne (EPFL), BSP-415, 1015 Lausanne, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23925114" target="_blank"〉PubMed〈/a〉
    Keywords: Acinetobacter/genetics/metabolism ; Bacterial Proteins/*chemistry/*secretion ; Bacterial Secretion Systems/*genetics ; Microsatellite Repeats/*physiology ; Protein Binding ; Vibrio cholerae/genetics/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2019
    Description: 〈sec〉〈st〉Synopsis〈/st〉〈p〉〈textbox textbox-type="graphic"〉〈p〉〈inline-fig〉〈/inline-fig〉〈/p〉〈/textbox〉〈/p〉 〈p〉The attachment and host envelope penetration mechanism of bacteriophages that employ a rigid tube/contractile sheath complex for infection of Gram-positive bacteria is poorly understood. This study describes the structure of the 〈i〉Listeria〈/i〉 phage A511 contractile tail in the pre- and post-host attachment state.〈/p〉 〈p〉 〈l type="unord"〉〈li〉〈p〉The A511 baseplate-tail fiber complex undergoes a massive conformational change and switches from threefold to sixfold symmetry upon attachment to the host cell.〈/p〉〈/li〉 〈li〉〈p〉The distal tail fiber protein gp108 attaches to the host cell wall before the sheath contracts.〈/p〉〈/li〉 〈li〉〈p〉The proximal part of the tail fiber carries two pyramids that are formed by gp106 trimers.〈/p〉〈/li〉 〈li〉〈p〉The gp106 pyramids reorient to point toward the cell surface, change their conformation to protrude attachment domain, and bind to the cell wall.〈/p〉〈/li〉 〈li〉〈p〉Contraction of the phage tail sheath assembly starts at the baseplate and propagates through the sheath in a wave-like motion.〈/p〉〈/li〉〈/l〉 〈/p〉〈/sec〉
    Print ISSN: 0261-4189
    Electronic ISSN: 1460-2075
    Topics: Biology , Medicine
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  • 4
    Publication Date: 2019
    Description: 〈p〉Contractile injection systems (bacteriophage tails, type VI secretions system, R-type pyocins, etc.) utilize a rigid tube/contractile sheath assembly for breaching the envelope of bacterial and eukaryotic cells. Among contractile injection systems, bacteriophages that infect Gram-positive bacteria represent the least understood members. Here, we describe the structure of 〈i〉Listeria〈/i〉 bacteriophage A511 tail in its pre- and post-host attachment states (extended and contracted, respectively) using cryo-electron microscopy, cryo-electron tomography, and X-ray crystallography. We show that the structure of the tube-baseplate complex of A511 is similar to that of phage T4, but the A511 baseplate is decorated with different receptor-binding proteins, which undergo a large structural transformation upon host attachment and switch the symmetry of the baseplate-tail fiber assembly from threefold to sixfold. For the first time under native conditions, we show that contraction of the phage tail sheath assembly starts at the baseplate and propagates through the sheath in a domino-like motion.〈/p〉
    Print ISSN: 0261-4189
    Electronic ISSN: 1460-2075
    Topics: Biology , Medicine
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  • 5
    ISSN: 1608-3040
    Keywords: bacteriophage T4 ; protein folding ; adhesin ; fibritin ; protein engineering ; fibrous proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Gene product 12 of bacteriophage T4, adhesin, serves to adhere the virus to host cells. Adhesin is a fibrous homotrimer, and a novel tertiary structure element, a β-helix, is supposed to be a major structural feature of this protein. We have constructed two truncated gp12 mutants, 12N1 and 12N2, containing 221 and 135 N-terminal residues, respectively. When expressed in E. coli cells, these gp12 fragments formed labile β-structural trimers. Another hybrid protein, 12FN, containing 179 N-terminal amino acid residues of gp12 fused to the C-terminal domain (31 amino acids) of T4 fibritin, was shown to have a trimeric proteolytically resistant a-helical structure. This structure is probably similar to that of fibritin, which has a triple α-helical coiled-coil structure. Hence, we have demonstrated the possibility of global transformation of fibrous protein structure using fusion with a C-terminal domain that initiates trimerization.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2016-03-31
    Description: Capsular polysaccharides (CPSs), from Acinetobacter baumannii isolates 1432, 4190 and NIPH 70, which have related gene content at the K locus, were examined, and the chemical structures established using 2D 1 H and 13 C NMR spectroscopy. The three isolates produce the same pentasaccharide repeat unit, which consists of 5- N -acetyl-7- N -[( S )-3-hydroxybutanoyl] (major) or 5,7-di- N -acetyl (minor) derivatives of 5,7-diamino-3,5,7,9-tetradeoxy- d - glycero - d - galacto -non-2-ulosonic (legionaminic) acid (Leg5Ac7R), d -galactose, N -acetyl- d -galactosamine and N -acetyl- d -glucosamine. However, the linkage between repeat units in NIPH 70 was different to that in 1432 and 4190, and this significantly alters the CPS structure. The KL27 gene cluster in 4190 and KL44 gene cluster in NIPH 70 are organized identically and contain lga genes for Leg5Ac7R synthesis, genes for the synthesis of the common sugars, as well as an itrA2 initiating transferase and four glycosyltransferases genes. They share high-level nucleotide sequence identity for corresponding genes, but differ in the wzy gene encoding the Wzy polymerase. The Wzy proteins, which have different lengths and share no similarity, would form the unrelated linkages in the K27 and K44 structures. The linkages formed by the four shared glycosyltransferases were predicted by comparison with gene clusters that synthesize related structures. These findings unambiguously identify the linkages formed by Wzy K27 and Wzy K44 , and show that the presence of different wzy genes in otherwise closely related K gene clusters changes the structure of the CPS. This may affect its capacity as a protective barrier for A. baumannii .
    Print ISSN: 0959-6658
    Electronic ISSN: 1460-2423
    Topics: Biology , Medicine
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