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81.
Hans J. De Boeck Juliette M. G. Bloor Rien Aerts Michael Bahn Claus Beier Bridget A. Emmett Marc Estiarte Jos M. Grünzweig Aud H. Halbritter Petr Holub Anke Jentsch Karel Klem Juergen Kreyling Gyrgy Krel‐Dulay Klaus Steenberg Larsen Alexandru Milcu Jacques Roy Bjarni D. Sigurdsson Melinda D. Smith Marcelo Sternberg Vigdis Vandvik Thomas Wohlgemuth Ivan Nijs Alan K. Knapp 《Global Change Biology》2020,26(2):e6-e7
82.
To investigate the influence of the proto-oncogene c-MYC on tumor development in different epithelial tissues which secrete Clara Cell Secretory Protein (uteroglobin, UG), transgenic mouse lines were established expressing the human c-MYC proto-oncogene under the control of the rabbit UG-promoter. These mice expressed the c-MYC transgene in Clara cells and other UG expressing tissues like uterus and prostate. In the bronchioalveolar epithelium of the lung hyperplasias developed originating from Clara cells. Surprisingly, transgenics most frequently developed T-lymphoblastic lymphomas, a polycystic kidney phenotype and renal cell carcinoma derived from tubular epithelial cells, which are both tissues that had so far not been known to express UG. Immunohistological studies in UG/MYC transgenics and in a transgenic line (UG/eGFP) expressing Green Fluorescent Protein confirmed that the uteroglobin promoter is not only active in Clara cells, but also in tubular epithelial cells of the kidney and in lymphatic tissue. The UG/MYC transgenics will be useful to investigate the biochemical mechanisms underlying the development of carcinomas and the oncogenic properties of c-MYC in epithelial cells of various tissues. 相似文献
83.
Gra?yna Domańska Christian Motz Michael Meinecke Anke Harsman Panagiotis Papatheodorou Boris Reljic Elke A. Dian-Lothrop Antoine Galmiche Oliver Kepp Lars Becker Kathrin Günnewig Richard Wagner Joachim Rassow 《PLoS pathogens》2010,6(4)
The vacuolating toxin VacA, released by Helicobacter pylori, is an important virulence factor in the pathogenesis of gastritis and gastroduodenal ulcers. VacA contains two subunits: The p58 subunit mediates entry into target cells, and the p34 subunit mediates targeting to mitochondria and is essential for toxicity. In this study we found that targeting to mitochondria is dependent on a unique signal sequence of 32 uncharged amino acid residues at the p34 N-terminus. Mitochondrial import of p34 is mediated by the import receptor Tom20 and the import channel of the outer membrane TOM complex, leading to insertion of p34 into the mitochondrial inner membrane. p34 assembles in homo-hexamers of extraordinary high stability. CD spectra of the purified protein indicate a content of >40% β-strands, similar to pore-forming β-barrel proteins. p34 forms an anion channel with a conductivity of about 12 pS in 1.5 M KCl buffer. Oligomerization and channel formation are independent both of the 32 uncharged N-terminal residues and of the p58 subunit of the toxin. The conductivity is efficiently blocked by 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), a reagent known to inhibit VacA-mediated apoptosis. We conclude that p34 essentially acts as a small pore-forming toxin, targeted to the mitochondrial inner membrane by a special hydrophobic N-terminal signal. 相似文献
84.
Anke Meyerdierks Michael Kube Ivaylo Kostadinov Hanno Teeling Frank Oliver Glöckner Richard Reinhardt Rudolf Amann 《Environmental microbiology》2010,12(2):422-439
Microbial consortia mediating the anaerobic oxidation of methane with sulfate are composed of methanotrophic Archaea (ANME) and Bacteria related to sulfate‐reducing Deltaproteobacteria. Cultured representatives are not available for any of the three ANME clades. Therefore, a metagenomic approach was applied to assess the genetic potential of ANME‐1 archaea. In total, 3.4 Mbp sequence information was generated based on metagenomic fosmid libraries constructed directly from a methanotrophic microbial mat in the Black Sea. These sequence data represent, in 30 contigs, about 82–90% of a composite ANME‐1 genome. The dataset supports the hypothesis of a reversal of the methanogenesis pathway. Indications for an assimilatory, but not for a dissimilatory sulfate reduction pathway in ANME‐1, were found. Draft genome and expression analyses are consistent with acetate and formate as putative electron shuttles. Moreover, the dataset points towards downstream electron‐accepting redox components different from the ones known from methanogenic archaea. Whereas catalytic subunits of [NiFe]‐hydrogenases are lacking in the dataset, genes for an [FeFe]‐hydrogenase homologue were identified, not yet described to be present in methanogenic archaea. Clustered genes annotated as secreted multiheme c‐type cytochromes were identified, which have not yet been correlated with methanogenesis‐related steps. The genes were shown to be expressed, suggesting direct electron transfer as an additional possible mode to shuttle electrons from ANME‐1 to the bacterial sulfate‐reducing partner. 相似文献
85.
Vera Kozjak-Pavlovic Elke A. Dian-Lothrop Michael Meinecke Oliver Kepp Katharina Ross Krishnaraj Rajalingam Anke Harsman Eva Hauf Volker Brinkmann Dirk Günther Ines Herrmann Robert Hurwitz Joachim Rassow Richard Wagner Thomas Rudel 《PLoS pathogens》2009,5(10)
The bacterial PorB porin, an ATP-binding β-barrel protein of pathogenic Neisseria gonorrhoeae, triggers host cell apoptosis by an unknown mechanism. PorB is targeted to and imported by host cell mitochondria, causing the breakdown of the mitochondrial membrane potential (ΔΨm). Here, we show that PorB induces the condensation of the mitochondrial matrix and the loss of cristae structures, sensitizing cells to the induction of apoptosis via signaling pathways activated by BH3-only proteins. PorB is imported into mitochondria through the general translocase TOM but, unexpectedly, is not recognized by the SAM sorting machinery, usually required for the assembly of β-barrel proteins in the mitochondrial outer membrane. PorB integrates into the mitochondrial inner membrane, leading to the breakdown of ΔΨm. The PorB channel is regulated by nucleotides and an isogenic PorB mutant defective in ATP-binding failed to induce ΔΨm loss and apoptosis, demonstrating that dissipation of ΔΨm is a requirement for cell death caused by neisserial infection. 相似文献
86.
聚乙烯吡咯烷酮制作鱼类透明骨骼标本 总被引:1,自引:0,他引:1
在传统透明骨骼标本制作方法基础上进行了改进,将标本经过高分子化合物——聚乙烯吡咯烷酮(PVP)处理后,制成的透明骨骼标本无需浸泡在丙三醇中保存,且具防霉防虫的特点。 相似文献
87.
Stroh A Anderka O Pfeiffer K Yagi T Finel M Ludwig B Schägger H 《The Journal of biological chemistry》2004,279(6):5000-5007
Stable supercomplexes of bacterial respiratory chain complexes III (ubiquinol:cytochrome c oxidoreductase) and IV (cytochrome c oxidase) have been isolated as early as 1985 (Berry, E. A., and Trumpower, B. L. (1985) J. Biol. Chem. 260, 2458-2467). However, these assemblies did not comprise complex I (NADH:ubiquinone oxidoreductase). Using the mild detergent digitonin for solubilization of Paracoccus denitrificans membranes we could isolate NADH oxidase, assembled from complexes I, III, and IV in a 1:4:4 stoichiometry. This is the first chromatographic isolation of a complete "respirasome." Inactivation of the gene for tightly bound cytochrome c552 did not prevent formation of this supercomplex, indicating that this electron carrier protein is not essential for structurally linking complexes III and IV. Complex I activity was also found in the membranes of mutant strains lacking complexes III or IV. However, no assembled complex I but only dissociated subunits were observed following the same protocols used for electrophoretic separation or chromatographic isolation of the supercomplex from the wild-type strain. This indicates that the P. denitrificans complex I is stabilized by assembly into the NADH oxidase supercomplex. In addition to substrate channeling, structural stabilization of a membrane protein complex thus appears as one of the major functions of respiratory chain supercomplexes. 相似文献
88.
Pearce FG Dobson RC Weber A Lane LA McCammon MG Squire MA Perugini MA Jameson GB Robinson CV Gerrard JA 《Biochemistry》2008,47(46):12108-12117
Dihydrodipicolinate synthase (DHDPS) is a tetrameric enzyme that is the first enzyme unique to the ( S)-lysine biosynthetic pathway in plants and bacteria. Previous studies have looked at the important role of Tyr107, an amino acid residue located at the tight-dimer interface between two monomers, in participating in a catalytic triad of residues during catalysis. In this study, we examine the importance of this residue in determining the quaternary structure of the DHDPS enzyme. The Tyr107 residue was mutated to tryptophan, and structural, biophysical, and kinetic studies were carried out on the mutant enzyme. These revealed that while the solid-state structure of the mutant enzyme was largely unchanged, as judged by X-ray crystallography, it exists as a mixture of primarily monomer and tetramer in solution, as determined by analytical ultracentrifugation, size-exclusion chromatography, and mass spectrometry. The catalytic ability of the DHDPS enzyme was reduced by the mutation, which also allowed the adventitious binding of alpha-ketoglutarate to the active site. A reduction in the apparent melting temperature of the mutant enzyme was observed. Thus, the tetrameric quaternary structure of DHDPS is critical to controlling specificity, heat stability, and intrinsic activity. 相似文献
89.
90.
Tannert A Kurz A Erlemann KR Müller K Herrmann A Schiller J Töpfer-Petersen E Manjunath P Müller P 《European biophysics journal : EBJ》2007,36(4-5):461-475
The bovine seminal plasma protein PDC-109 modulates the maturation of bull sperm cells by removing lipids, mainly phosphatidylcholine
and cholesterol, from their cellular membrane. Here, we have characterized the process of extraction of endogenous phospholipids
and of their respective analogues. By measuring the PDC-109-mediated release of fluorescent phospholipid analogues from lipid
vesicles and from biological membranes (human erythrocytes, bovine epididymal sperm cells), we showed that PDC-109 extracts
phospholipids with a phosphorylcholine headgroup mainly from the outer leaflet of these membranes. The ability of PDC-109
to extract endogenous phospholipids from epididymal sperm cells was followed by mass spectrometry, which allowed us to characterize
the fatty acid pattern of the released lipids. From these cells, PDC-109 extracted phosphatidylcholine and sphingomyelin that
contained an enrichment of mono- and di-unsaturated fatty acids as well as short-chain and lyso-phosphatidylcholine species.
Based on the results, a model explaining the phospholipid specificity of PDC-109-mediated lipid release is presented.
Astrid Tannert and Anke Kurz have contributed equally to this work.
Dedicated to Prof. K. Arnold on the occasion of his 65th birthday. 相似文献