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  • 1
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    The structure of a cytolytic alpha-helical toxin pore reveals its assembly mechanism (2009)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2009-05-08
    Description: Pore-forming toxins (PFTs) are a class of potent virulence factors that convert from a soluble form to a membrane-integrated pore. They exhibit their toxic effect either by destruction of the membrane permeability barrier or by delivery of toxic components through the pores. Among the group of bacterial PFTs are some of the most dangerous toxins, such as diphtheria and anthrax toxin. Examples of eukaryotic PFTs are perforin and the membrane-attack complex, proteins of the immune system. PFTs can be subdivided into two classes, alpha-PFTs and beta-PFTs, depending on the suspected mode of membrane integration, either by alpha-helical or beta-sheet elements. The only high-resolution structure of a transmembrane PFT pore is available for a beta-PFT--alpha-haemolysin from Staphylococcus aureus. Cytolysin A (ClyA, also known as HlyE), an alpha-PFT, is a cytolytic -helical toxin responsible for the haemolytic phenotype of several Escherichia coli and Salmonella enterica strains. ClyA is cytotoxic towards cultured mammalian cells, induces apoptosis of macrophages and promotes tissue pervasion. Electron microscopic reconstructions demonstrated that the soluble monomer of ClyA must undergo large conformational changes to form the transmembrane pore. Here we report the 3.3 A crystal structure of the 400 kDa dodecameric transmembrane pore formed by ClyA. The tertiary structure of ClyA protomers in the pore is substantially different from that in the soluble monomer. The conversion involves more than half of all residues. It results in large rearrangements, up to 140 A, of parts of the monomer, reorganization of the hydrophobic core, and transitions of -sheets and loop regions to -helices. The large extent of interdependent conformational changes indicates a sequential mechanism for membrane insertion and pore formation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mueller, Marcus -- Grauschopf, Ulla -- Maier, Timm -- Glockshuber, Rudi -- Ban, Nenad -- England -- Nature. 2009 Jun 4;459(7247):726-30. doi: 10.1038/nature08026.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19421192" target="_blank"〉PubMed〈/a〉
    Keywords: Cell Membrane/chemistry ; Crystallography, X-Ray ; Escherichia coli K12/*chemistry ; Escherichia coli Proteins/*chemistry ; Hemolysin Proteins/*chemistry ; Membrane Proteins/*chemistry ; *Models, Molecular ; *Protein Folding ; Protein Structure, Tertiary
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
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    Architecture of mammalian fatty acid synthase at 4.5 A resolution (2006)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 2006-03-04
    Description: The homodimeric mammalian fatty acid synthase is one of the most complex cellular multienzymes, in that each 270-kilodalton polypeptide chain carries all seven functional domains required for fatty acid synthesis. We have calculated a 4.5 angstrom-resolution x-ray crystallographic map of porcine fatty acid synthase, highly homologous to the human multienzyme, and placed homologous template structures of all individual catalytic domains responsible for the cyclic elongation of fatty acid chains into the electron density. The positioning of domains reveals the complex architecture of the multienzyme forming an intertwined dimer with two lateral semicircular reaction chambers, each containing a full set of catalytic domains required for fatty acid elongation. Large distances between active sites and conformational differences between the reaction chambers demonstrate that mobility of the acyl carrier protein and general flexibility of the multienzyme must accompany handover of the reaction intermediates during the reaction cycle.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Maier, Timm -- Jenni, Simon -- Ban, Nenad -- New York, N.Y. -- Science. 2006 Mar 3;311(5765):1258-62.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Molecular Biology and Biophysics, Department of Biology, Swiss Federal Institute of Technology (ETH Zurich), 8093 Zurich, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16513975" target="_blank"〉PubMed〈/a〉
    Keywords: Acyl Carrier Protein/chemistry/metabolism ; Animals ; Binding Sites ; Catalytic Domain ; Crystallization ; Crystallography, X-Ray ; Dimerization ; Fatty Acid Synthases/*chemistry/isolation & purification/metabolism ; Fatty Acids/biosynthesis ; Mammary Glands, Animal/enzymology ; Models, Molecular ; Protein Conformation ; Protein Folding ; Protein Structure, Quaternary ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Protein Subunits/chemistry ; Swine
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
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    Architecture of a fungal fatty acid synthase at 5 A resolution (2006)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2006-03-04
    Description: All steps of fatty acid synthesis in fungi are catalyzed by the fatty acid synthase, which forms a 2.6-megadalton alpha6beta6 complex. We have determined the molecular architecture of this multienzyme by fitting the structures of homologous enzymes that catalyze the individual steps of the reaction pathway into a 5 angstrom x-ray crystallographic electron density map. The huge assembly contains two separated reaction chambers, each equipped with three sets of active sites separated by distances up to approximately 130 angstroms, across which acyl carrier protein shuttles substrates during the reaction cycle. Regions of the electron density arising from well-defined structural features outside the catalytic domains separate the two reaction chambers and serve as a matrix in which domains carrying the various active sites are embedded. The structure rationalizes the compartmentalization of fatty acid synthesis, and the spatial arrangement of the active sites has specific implications for our understanding of the reaction cycle mechanism and of the architecture of multienzymes in general.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jenni, Simon -- Leibundgut, Marc -- Maier, Timm -- Ban, Nenad -- New York, N.Y. -- Science. 2006 Mar 3;311(5765):1263-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Molecular Biology and Biophysics, Department of Biology, Swiss Federal Institute of Technology (ETH Zurich), 8093 Zurich, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16513976" target="_blank"〉PubMed〈/a〉
    Keywords: Acyl Carrier Protein/chemistry/metabolism ; Ascomycota/*enzymology ; Binding Sites ; Catalytic Domain ; Crystallization ; Crystallography, X-Ray ; Dimerization ; Fatty Acid Synthases/*chemistry/isolation & purification/metabolism ; Fatty Acids/biosynthesis ; Models, Molecular ; Protein Conformation ; Protein Folding ; Protein Structure, Quaternary ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Sequence Homology, Amino Acid
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
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    The crystal structure of a mammalian fatty acid synthase (2008)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2008-09-06
    Description: Mammalian fatty acid synthase is a large multienzyme that catalyzes all steps of fatty acid synthesis. We have determined its crystal structure at 3.2 angstrom resolution covering five catalytic domains, whereas the flexibly tethered terminal acyl carrier protein and thioesterase domains remain unresolved. The structure reveals a complex architecture of alternating linkers and enzymatic domains. Substrate shuttling is facilitated by flexible tethering of the acyl carrier protein domain and by the limited contact between the condensing and modifying portions of the multienzyme, which are mainly connected by linkers rather than direct interaction. The structure identifies two additional nonenzymatic domains: (i) a pseudo-ketoreductase and (ii) a peripheral pseudo-methyltransferase that is probably a remnant of an ancestral methyltransferase domain maintained in some related polyketide synthases. The structural comparison of mammalian fatty acid synthase with modular polyketide synthases shows how their segmental construction allows the variation of domain composition to achieve diverse product synthesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Maier, Timm -- Leibundgut, Marc -- Ban, Nenad -- New York, N.Y. -- Science. 2008 Sep 5;321(5894):1315-22. doi: 10.1126/science.1161269.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Molecular Biology and Biophysics, ETH Zurich, 8092 Zurich, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18772430" target="_blank"〉PubMed〈/a〉
    Keywords: Acyl Carrier Protein/chemistry/metabolism ; Amino Acid Sequence ; Animals ; Binding Sites ; Catalytic Domain ; Crystallography, X-Ray ; Dimerization ; Evolution, Molecular ; Fatty Acid Synthase, Type I/*chemistry ; Fatty Acids/biosynthesis ; Methyltransferases/chemistry ; Models, Molecular ; Molecular Sequence Data ; NADP/chemistry/metabolism ; Polyketide Synthases/chemistry/metabolism ; Protein Conformation ; Protein Folding ; Protein Structure, Tertiary ; Swine/*metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
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    Architecture of human mTOR complex 1 (2015)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2015-12-19
    Description: Target of rapamycin (TOR), a conserved protein kinase and central controller of cell growth, functions in two structurally and functionally distinct complexes: TORC1 and TORC2. Dysregulation of mammalian TOR (mTOR) signaling is implicated in pathologies that include diabetes, cancer, and neurodegeneration. We resolved the architecture of human mTORC1 (mTOR with subunits Raptor and mLST8) bound to FK506 binding protein (FKBP)-rapamycin, by combining cryo-electron microscopy at 5.9 angstrom resolution with crystallographic studies of Chaetomium thermophilum Raptor at 4.3 angstrom resolution. The structure explains how FKBP-rapamycin and architectural elements of mTORC1 limit access to the recessed active site. Consistent with a role in substrate recognition and delivery, the conserved amino-terminal domain of Raptor is juxtaposed to the kinase active site.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Aylett, Christopher H S -- Sauer, Evelyn -- Imseng, Stefan -- Boehringer, Daniel -- Hall, Michael N -- Ban, Nenad -- Maier, Timm -- New York, N.Y. -- Science. 2016 Jan 1;351(6268):48-52. doi: 10.1126/science.aaa3870. Epub 2015 Dec 17.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland. ; Biozentrum, University of Basel, Basel, Switzerland. ; Biozentrum, University of Basel, Basel, Switzerland. ban@mol.biol.ethz.ch m.hall@unibas.ch timm.maier@unibas.ch. ; Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland. ban@mol.biol.ethz.ch m.hall@unibas.ch timm.maier@unibas.ch.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26678875" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptor Proteins, Signal Transducing/*chemistry ; Catalytic Domain ; Cryoelectron Microscopy ; Humans ; Multiprotein Complexes/*chemistry ; Protein Binding ; Protein Multimerization ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Substrate Specificity ; TOR Serine-Threonine Kinases/*chemistry ; Tacrolimus Binding Proteins/*chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
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    Mycocerosic acid synthase exemplifies the architecture of reducing polyketide synthases (2016)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2016-03-16
    Description: Polyketide synthases (PKSs) are biosynthetic factories that produce natural products with important biological and pharmacological activities. Their exceptional product diversity is encoded in a modular architecture. Modular PKSs (modPKSs) catalyse reactions colinear to the order of modules in an assembly line, whereas iterative PKSs (iPKSs) use a single module iteratively as exemplified by fungal iPKSs (fiPKSs). However, in some cases non-colinear iterative action is also observed for modPKSs modules and is controlled by the assembly line environment. PKSs feature a structural and functional separation into a condensing and a modifying region as observed for fatty acid synthases. Despite the outstanding relevance of PKSs, the detailed organization of PKSs with complete fully reducing modifying regions remains elusive. Here we report a hybrid crystal structure of Mycobacterium smegmatis mycocerosic acid synthase based on structures of its condensing and modifying regions. Mycocerosic acid synthase is a fully reducing iPKS, closely related to modPKSs, and the prototype of mycobacterial mycocerosic acid synthase-like PKSs. It is involved in the biosynthesis of C20-C28 branched-chain fatty acids, which are important virulence factors of mycobacteria. Our structural data reveal a dimeric linker-based organization of the modifying region and visualize dynamics and conformational coupling in PKSs. On the basis of comparative small-angle X-ray scattering, the observed modifying region architecture may be common also in modPKSs. The linker-based organization provides a rationale for the characteristic variability of PKS modules as a main contributor to product diversity. The comprehensive architectural model enables functional dissection and re-engineering of PKSs.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Herbst, Dominik A -- Jakob, Roman P -- Zahringer, Franziska -- Maier, Timm -- England -- Nature. 2016 Mar 24;531(7595):533-7. doi: 10.1038/nature16993. Epub 2016 Mar 14.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26976449" target="_blank"〉PubMed〈/a〉
    Keywords: Acyltransferases/*chemistry/*metabolism ; Crystallography, X-Ray ; Fatty Acid Synthases/metabolism ; Models, Molecular ; Mycobacterium smegmatis/enzymology ; Oxidation-Reduction ; Polyketide Synthases/*chemistry/*metabolism ; Protein Structure, Tertiary ; Virulence Factors
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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