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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