Die Verteilungsmechanismen von β-barrel-Proteinen in Pflanzenzellen(S. 127)
Anna Klinger, Roman Ladig, Enrico Schleiff
Mitochondria and plastids contain nuclear encoded β-barrel proteins in their outer membranes required for the exchange of metabolites and solutes. The specificity of the outer membrane proteome of the two organelles calls for targeting mechanisms discriminating between them. In vivo approaches based on self-assembling green fluorescent protein (GFP) define the highly hydrophobic last β-hairpin serving as signal for β-barrel protein targeting to mitochondria and maybe as “bouncing off” signal for plastids.
Bislang stärkster molekularer Motor zieht Bakterien über Oberflächen(S. 130)
Anke Treuner-Lange, Lotte Søgaard-Andersen
Type IV pili (T4P) are filamentous cell surface structures found in many bacteria. They are involved in important processes including motility, adhesion, and biofilm formation. T4P are highly dynamic and undergo cycles of extension, adhesion, and retraction. The structure of the machine driving these cycles remained unknown. We recently elucidated the architecture of this machine in Myxococcus xanthus and showed that it spans the entire cell envelope. We propose a testable working model how the pilus filament is extended and retracted.
Eine neue Sicht auf die Lichtwahrnehmung durch Bakterien(S. 135)
Nils Schürgers, Annegret Wilde
The phototactic cyanobacterium Synechocystis spec. PCC 6803 is spherical, two to three micrometer in diameter, and can directly and accurately perceive the position of a light source and consequently move into this direction. The cell body acts as a very effective spherical microlens, focusing a sharp image of the light source close to the non-illuminated side of the cell. We predict that this lensing effect leads to the inactivation of type IV pili on the far side of the light source whereas they assemble on the front side to pull the cells towards the light source.
Verhaltensphänotypisierung von Mäusen(S. 138)
Sabine M. Hölter
According to the recent global burden of disease study of the World Health Organisation, mental and neurological disorders account for a substantial proportion of the world’s disease burden. In complex diseases, both life style and genetic predisposition contribute to disease development. The mouse has become a valuable animal model to understand di - sease etiology and to develop therapies, because mice can be easily genetically modified, and many disease symptoms can be readily measured in mice.
Leitmolekülsuche mit DNA-codierten Bibliotheken(S. 142)
Markus G. Rudolph
Structure-based drug design requires lead molecules, which traditionally are found by tedious and expensive screening campaigns. By contrast, screening of DNA-encoded small molecule libraries can be much more efficient. Here, the principle and application of the recently developed DNA-encoded library technology (DELT) are discussed.
Künstliche Evolution des genetischen Codes von Mikroorganismen(S. 146)
Jan-Stefam Völler, Michael Georg Hösl, Nediljko Budisa
The experimental evolution of microorganisms to highly efficient pro - ducers of biomolecules has a long tradition in industrial biotechnology. Its combination with synthetic biology and xenobiology can be used for the creation of a new, artificial biodiversity. Here, we describe evolution experiments for the development of robust bacterial strains harboring a new chemical composition of their proteomes. These strains might be beneficial for the production of amino acid modified proteins/peptides.
Designer-Rekombinasen für präzises Genome Editing(S. 151)
Frank Buchholz, Janet Karpinski, Martin Schneider, Felix Lansing, Joachim Hauber
Site-specific recombinases have long been used as powerful research tools to engineer the genome of model organisms. We have expanded the utility of recombinases by re-directing their DNA binding specificity to predefined target sequences naturally occurring in the genome of HIV-1. In contrast to programmable nucleases, such designer recombinases possess the unique ability to fulfill precise cleavage and immediate resealing of the respective DNA lesion in vivo.
Genom-Editierung – neue Wege im klinischen Alltag(S. 155)
Viviane Dettmer, Toni Cathomen, Markus Hildenbeutel
Programmable nucleases, such as zinc finger nucleases, TALE nucleases, and CRISPR-Cas nucleases, allow for the introduction of precise modifications in the human genome. As a consequence, targeted genome editing has heralded a new area for gene therapy and the treatment of acquired and inherited disorders. Here, we describe the concept of designer nuclease- mediated genome engineering, discuss risks and potential limitations of its usage, highlight some of the achieved milestones, and review the most prominent studies that have made it from the laboratory to the clinic.
Genome Engineering mit CRISPR/Cas – Revolution in der Pflanzenzüchtung(S. 159)
Felix Wolter, Holger Puchta
The CRISPR/Cas system has revolutionized plant genome engineering. Non homologous end joining mediated targeted mutagenesis is now a routine procedure including crop plants, and remarkable progress was made to further enhance specificity by a paired nickase approach. Moreover, predefined changes can be introduced by homologous recombination. Even more sophisticated techniques are being developed at the moment to restructure plant genomes on a more global level or to redirect gene expression.
Anwendungen & Produkte
Ein neuartiger Assay zur Messung chemotaktischer Migration in Echtzeit(S. 171)
Lindy O´Clair, Bernhard Ellinger, Milena Kalmer, Clare Szybut, Yvonne Borsetti
Traditional techniques for studying chemotaxis, such as Boyden chamber assays, are limited due to their endpoint nature and inability to visualize cells. A novel technique is presented that generates kinetic, automated, image-based measurements and movies of chemotaxis in a reproducible 96-well format. This technique offers the advantages of visual confirmation of migration and morphology, reduced cell requirement and the use of biologically relevant surface substrates, with or without fluorescent labels.
Bekämpfung von resistenten Krankenhauskeimen: Inhibition von Biofilmen(S. 215)
Frauke Symanowski, Veronika Hellwig, Christian Grünewald, Uwe Englisch
Bacterial biofilms attached on surfaces of implants cause nosocomial infections. The polysaccharide poly-β(1-6)-N-acetylglucosamine (PNAG) forms the backbone of Staphylococcus biofilms. A target for drugs to treat these infections is the inhibition of biofilm synthesis and stabilization of PNAG. A promising source of inhibitors are macroalgae, because they have many interactions with bacterial biofilm systems. Isolation and characterization of those inhibitors are our research topic.
Bestimmung bakterieller Haftkräfte durch gezielte Scherkrafteinwirkung(S. 218)
Hans-Achim Reimann, Kerstin Lohbauer, Philipp Häfner, Nathalie Stefani
Research in the field of bioadhesion is crucial to determine the antimicrobial efficacy. Experiments include cultivations with Escherichia coli K12 JM109 to reach bacteria adhesion in order to enable adhesion force measurements between bacterium and surface with a new micromanipulation system installed in atomic force microscope. To alter the surface, hydrophobic surfaces were generated with Argon/C4F8 plasma. The findings demonstrate the successful validation of the new micromanipulation system to measure the bacterial adhesion force and additionally show the antiadhesive effect of fluorine.
Bioelektrokalorimetrie – der mikrobielle elektrochemische Peltier-Effekt(S. 220)
Falk Harnisch, Benjamin Korth, Thomas Maskow
Based on the development of bioelectrocalorimetry, allowing the first measurements of heat production of electroactive microorganisms, the microbial electrochemical Peltier effect was discovered. This effect represents an entropic barrier at the interface of an electroactive microorganism and an insoluble electron acceptor during extracellular electron transfer. As for Geobacteraceae based anodes an investment of energy for overcoming this barrier is required, the microbial energy gain is lowered.