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David Veesler - One of the best experts on this subject based on the ideXlab platform.
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Structure of the type VI secretion system TssK–TssF–TssG Baseplate subcomplex revealed by cryo-electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 Å resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture. Type VI secretion systems (T6SSs) translocate effector proteins into eukaryotic and bacterial recipient cells and are present in many Gram-negative bacteria. Here the authors present the 3.7 Å cryoEM structure of the E.coli T6SS Baseplate wedge comprising TssK–TssF–TssG and propose a model for the T6SS Baseplate and needle complex.
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structure of the type vi secretion system tssk tssf tssg Baseplate subcomplex revealed by cryo electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 A resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture. Type VI secretion systems (T6SSs) translocate effector proteins into eukaryotic and bacterial recipient cells and are present in many Gram-negative bacteria. Here the authors present the 3.7 A cryoEM structure of the E.coli T6SS Baseplate wedge comprising TssK–TssF–TssG and propose a model for the T6SS Baseplate and needle complex.
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Structure of the type VI secretion system TssK–TssF–TssG Baseplate subcomplex revealed by cryo-electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 Å resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture.
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Structure, Adsorption to Host, and Infection Mechanism of Virulent Lactococcal Phage p2
Journal of Virology, 2013Co-Authors: Cecilia Bebeacua, David Veesler, Sylvain Moineau, Denise Tremblay, Carine Farenc, Marie-pierre Chapot-chartier, Irina Sadovskaya, Marin Van Heel, Christian CambillauAbstract:Lactococcal siphophages from the 936 and P335 groups infect the Gram-positive bacterium Lactococcus lactis using receptor binding proteins (RBPs) attached to their Baseplate, a large multiprotein complex at the distal part of the tail. We have previously reported the crystal and electron microscopy (EM) structures of the Baseplates of phages p2 (936 group) and TP901-1 (P335 group) as well as the full EM structure of the TP901-1 virion. Here, we report the complete EM structure of siphophage p2, including its capsid, connector complex, tail, and Baseplate. Furthermore, we show that the p2 tail is characterized by the presence of protruding decorations, which are related to adhesins and are likely contributed by the major tail protein C-terminal domains. This feature is reminiscent of the tail of Escherichia coli phage lambda and Bacillus subtilis phage SPP1 and might point to a common mechanism for establishing initial interactions with their bacterial hosts. Comparative analyses showed that the architecture of the phage p2 Baseplate differs largely from that of lactococcal phage TP901-1. We quantified the interaction of its RBP with the saccharidic receptor and determined that specificity is due to lower k(off) values of the RBP/saccharidic dissociation. Taken together, these results suggest that the infection of L. lactis strains by phage p2 is a multistep process that involves reversible attachment, followed by Baseplate activation, specific attachment of the RBPs to the saccharidic receptor, and DNA ejection.
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Unraveling Lactococcal Phage Baseplate Assembly by Mass Spectrometry
Molecular & Cellular Proteomics, 2011Co-Authors: Dale A. Shepherd, Julie Lichiere, David Veesler, Alison E. Ashcroft, Christian CambillauAbstract:Bacteriophages belonging to the Caudovirales order possess a tail acting as a molecular machine used during infection to recognize the host and ensure high-efficiency genome delivery to the cell cytoplasm. They bear a large and sophisticated multiprotein organelle at their distal tail end, either a Baseplate or a tail-tip, which is the control center for infectivity. We report here insights into the Baseplate assembly pathways of two lactoccocal phages (p2 and TP901–1) using electrospray ionization-mass spectrometry. Based on our “block cloning” strategy we have expressed large complexes of their Baseplates as well as several significant structural subcomplexes. Previous biophysical characterization using size-exclusion chromatography coupled with on-line light scattering and refractometry demonstrated that the overproduced recombinant proteins interact with each other to form large (up to 1.9 MDa) and stable assemblies. The structures of several of these complexes have been determined by x-ray diffraction or by electron microscopy. In this contribution, we demonstrate that electrospray ionization-mass spectrometry yields accurate mass measurements for the different Baseplate complexes studied from which their stoichiometries can be discerned, and that the subspecies observed in the spectra provide valuable information on the assembly mechanisms of these large organelles.
Christian Cambillau - One of the best experts on this subject based on the ideXlab platform.
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Structural Insights into Lactococcal Siphophage p2 Baseplate Activation Mechanism.
Viruses, 2020Co-Authors: Silvia Spinelli, Christian Cambillau, Denise M. Tremblay, Sylvain Moineau, Adeline GouletAbstract:Virulent phages infecting L. lactis, an industry-relevant bacterium, pose a significant risk to the quality of the fermented milk products. Phages of the Skunavirus genus are by far the most isolated lactococcal phages in the cheese environments and phage p2 is the model siphophage for this viral genus. The Baseplate of phage p2, which is used to recognize its host, was previously shown to display two conformations by X-ray crystallography, a rested state and an activated state ready to bind to the host. The Baseplate became only activated and opened in the presence of Ca2+. However, such an activated state was not previously observed in the virion. Here, using nanobodies binding to the Baseplate, we report on the negative staining electron microscopy structure of the activated form of the Baseplate directly observed in the p2 virion, that is compatible with the activated Baseplate crystal structure. Analyses of this new structure also established the presence of a second distal tail (Dit) hexamer as a component of the Baseplate, the topology of which differs largely from the first one. We also observed an uncoupling between the Baseplate activation and the tail tip protein (Tal) opening, suggesting an infection mechanism more complex than previously expected.
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Structure of the type VI secretion system TssK–TssF–TssG Baseplate subcomplex revealed by cryo-electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 Å resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture. Type VI secretion systems (T6SSs) translocate effector proteins into eukaryotic and bacterial recipient cells and are present in many Gram-negative bacteria. Here the authors present the 3.7 Å cryoEM structure of the E.coli T6SS Baseplate wedge comprising TssK–TssF–TssG and propose a model for the T6SS Baseplate and needle complex.
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structure of the type vi secretion system tssk tssf tssg Baseplate subcomplex revealed by cryo electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 A resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture. Type VI secretion systems (T6SSs) translocate effector proteins into eukaryotic and bacterial recipient cells and are present in many Gram-negative bacteria. Here the authors present the 3.7 A cryoEM structure of the E.coli T6SS Baseplate wedge comprising TssK–TssF–TssG and propose a model for the T6SS Baseplate and needle complex.
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Structure of the type VI secretion system TssK–TssF–TssG Baseplate subcomplex revealed by cryo-electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 Å resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture.
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Bacteriophage module reshuffling results in adaptive host range as exemplified by the Baseplate model of listerial phage A118.
Virology, 2015Co-Authors: Christian CambillauAbstract:Abstract Each phage infects its specific bacterial host strain through highly specific interactions between the Baseplate-associated receptor binding protein (RBP) at the tip of the phage tail and the receptor at the host surface. Baseplates incorporate structural core modules, Dit and Tal, largely conserved among phages, and peripheral modules anchoring the RBPs. Exploiting structural information from the HHpred program and EM data from the Bielmann et al. (2015) paper, a molecular model of the A118 phage Baseplate was generated from different building blocks. This model implies the occurrence of Baseplate module reshuffling and suggests that listerial phage A118 may have been derived from lactococcal phage TP901-1 through host species exchange. With the increase of available viral module structures, modelling phage Baseplates will become easier and more reliant, and will provide insightful information on the nature of the phage host receptor and its mode of recognition.
Young Jun Park - One of the best experts on this subject based on the ideXlab platform.
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Structure of the type VI secretion system TssK–TssF–TssG Baseplate subcomplex revealed by cryo-electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 Å resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture. Type VI secretion systems (T6SSs) translocate effector proteins into eukaryotic and bacterial recipient cells and are present in many Gram-negative bacteria. Here the authors present the 3.7 Å cryoEM structure of the E.coli T6SS Baseplate wedge comprising TssK–TssF–TssG and propose a model for the T6SS Baseplate and needle complex.
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structure of the type vi secretion system tssk tssf tssg Baseplate subcomplex revealed by cryo electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 A resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture. Type VI secretion systems (T6SSs) translocate effector proteins into eukaryotic and bacterial recipient cells and are present in many Gram-negative bacteria. Here the authors present the 3.7 A cryoEM structure of the E.coli T6SS Baseplate wedge comprising TssK–TssF–TssG and propose a model for the T6SS Baseplate and needle complex.
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Structure of the type VI secretion system TssK–TssF–TssG Baseplate subcomplex revealed by cryo-electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 Å resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture.
Kaitlyn D. Lacourse - One of the best experts on this subject based on the ideXlab platform.
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Structure of the type VI secretion system TssK–TssF–TssG Baseplate subcomplex revealed by cryo-electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 Å resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture. Type VI secretion systems (T6SSs) translocate effector proteins into eukaryotic and bacterial recipient cells and are present in many Gram-negative bacteria. Here the authors present the 3.7 Å cryoEM structure of the E.coli T6SS Baseplate wedge comprising TssK–TssF–TssG and propose a model for the T6SS Baseplate and needle complex.
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structure of the type vi secretion system tssk tssf tssg Baseplate subcomplex revealed by cryo electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 A resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture. Type VI secretion systems (T6SSs) translocate effector proteins into eukaryotic and bacterial recipient cells and are present in many Gram-negative bacteria. Here the authors present the 3.7 A cryoEM structure of the E.coli T6SS Baseplate wedge comprising TssK–TssF–TssG and propose a model for the T6SS Baseplate and needle complex.
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Structure of the type VI secretion system TssK–TssF–TssG Baseplate subcomplex revealed by cryo-electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 Å resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture.
Joseph D. Mougous - One of the best experts on this subject based on the ideXlab platform.
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Structure of the type VI secretion system TssK–TssF–TssG Baseplate subcomplex revealed by cryo-electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 Å resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture. Type VI secretion systems (T6SSs) translocate effector proteins into eukaryotic and bacterial recipient cells and are present in many Gram-negative bacteria. Here the authors present the 3.7 Å cryoEM structure of the E.coli T6SS Baseplate wedge comprising TssK–TssF–TssG and propose a model for the T6SS Baseplate and needle complex.
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structure of the type vi secretion system tssk tssf tssg Baseplate subcomplex revealed by cryo electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 A resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture. Type VI secretion systems (T6SSs) translocate effector proteins into eukaryotic and bacterial recipient cells and are present in many Gram-negative bacteria. Here the authors present the 3.7 A cryoEM structure of the E.coli T6SS Baseplate wedge comprising TssK–TssF–TssG and propose a model for the T6SS Baseplate and needle complex.
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Structure of the type VI secretion system TssK–TssF–TssG Baseplate subcomplex revealed by cryo-electron microscopy
Nature Communications, 2018Co-Authors: Young Jun Park, Christian Cambillau, Kaitlyn D. Lacourse, Joseph D. Mougous, Frank Dimaio, David VeeslerAbstract:Type VI secretion systems (T6SSs) translocate effectors into target cells and are made of a contractile sheath and a tube docked onto a multi-protein transmembrane complex via a Baseplate. Although some information is available about the mechanisms of tail contraction leading to effector delivery, the detailed architecture and function of the Baseplate remain unknown. Here, we report the 3.7 Å resolution cryo-electron microscopy reconstruction of an enteroaggregative Escherichia coli Baseplate subcomplex assembled from TssK, TssF and TssG. The structure reveals two TssK trimers interact with a locally pseudo-3-fold symmetrical complex comprising two copies of TssF and one copy of TssG. TssF and TssG are structurally related to each other and to components of the phage T4 Baseplate and of the type IV secretion system, strengthening the evolutionary relationships among these macromolecular machines. These results, together with bacterial two-hybrid assays, provide a structural framework to understand the T6SS Baseplate architecture.
