Rote Überlebenskünstler in Salzlagunen(S. 11)
Halobacterium is adapted to high salt concentrations of 5 M NaCl and even survives in salt crystals for hundreds of years. Bacteriorhodopsin, gas vesicles, and halophilic enzymes are specific traits used for biotechnological purposes. As archaeon, Halobacterium shows eukaryotic features in transcription, translation and replication. The microbe gained more than 1.000 metabolic genes from bacteria enabling heterotrophic growth in oxygen containing environments.
G-Quadruplex in DNA und RNA – Strukturen mit biologischer Funktion?(S. 14)
Hans J. Lipps, Jan Postberg
For many years it is known that nucleic acids containing runs of guanines can fold into four-stranded structures, G-quadruplexes, but often they were regarded as structural curiosity. Only recently evidence accumulated that these structures occur in vivo and may provide a nucleic-acidbased mechanism for the regulation of important biological processes. Here we review recent progress in understanding the biological function of G-quadruplex structures and the regulation of their formation and resolution in vivo.
Molybdän – vom Grundstoffwechsel zur Neurobiologie und Blutdruckregulation(S. 18)
Four molybdenum(Mo)-dependent enzymes are known in humans, each harboring a pterin-based Mo cofactor (Moco), which is synthesized by a conserved biosynthetic pathway. A deficiency in Moco results in a lethal neurodegenerative disorder, for which a therapy has been developed. Moco biosynthesis and enzymes present the origin of various cellular functions ranging from synaptogenesis to nitric oxide synthesis. Understanding this complex interplay aims to translate into new diagnostics and therapies.
Mitochondriale Transhydrogenase: Yin und Yang der antioxidativen Kapazität(S. 22)
Alfred von Hardernberg, Alexander Nickel, Christoph Maack
Mitochondria are the main source for ATP, but also reactive oxygen species (ROS). While NADH is required for ATP production, NADPH regenerates anti-oxidative capacity to prevent excessive ROS emission. The mitochondrial transhydrogenase links NADH with NADPH pools and is mutated in C57BL/6 mice from Jackson Laboratories. While in most scenarios, the transhydrogenase regenerates NADPH in the forward mode, it can reverse under pathological conditions and cause oxidative stress and heart failure.
Ein altes Paar in neuem Glanz: Thiosulfat und Tetrathionat(S. 25)
Julia Kurth, Christiane Dahl
Thiosulfate dehydrogenase (TsdA) enzymes represent a phylogenetically widespread family of periplasmic diheme cytochromes. They catalyze both thiosulfate oxidation and tetrathionate reduction. The reaction directionality of TsdA enzymes varies in dependence of the source organism. Currently, the best characterized TsdA enzymes are the thiosulfate-oxidizing enzyme from the purple sulfur bacterium Allochromatium vinosum and the tetrathionate-reducing enzyme from the human gut pathogen Campylobacter jejuni.
Simulation des Transports durch Außenmembrankanäle(S. 28)
Gram-negative bacteria feature an outer and an inner membrane. Especially the outer membrane provides an effective barrier for the entry of noxious substances, though at the same time ions, nutrients, and metabolites need to be able to get inside. Many of these substances either enter through general diffusion or through substrate-specific membrane pores. Over the last years, molecular dynamics simulations have become an extremely valuable tool for understanding the structurefunction relationship of membrane transport.
Reversible Palmitoylierung von Proteinen(S. 32)
Eliot Morrison, Hannah Wiedemann, Britta Brügger, Christian Freund
The covalent attachment of lipid moieties to proteins represents an important subclass of co- or post-translational modifications in the cell. The 16-carbon fully saturated lipid palmitate is preferentially conjugated to free cysteines of peripheral or integral membrane proteins. The thioester bond formed can be reversibly hydrolyzed and thereby modulates a proteins function with regard to trafficking, compartmentation within the membrane or lipid-induced conformational changes in a cyclic manner.
Entwicklung der genetischen Diagnostik(S. 37)
Dietrich August, Bodo Grimbacher
DNA sequencing has had large impact on basic research and medical diagnosis. In recent years, next generation sequencing technologies have increased the sequencing speed and turnaround by magnitudes and slashed the costs. Here, we summarize different approaches and give examples for their application in clinical settings.
Genombasierte Suche nach Protease-Inhibitoren aus bakteriellen Quellen(S. 41)
Felix Wolf, Leonard Kaysser
Bacteria are a rich source for small-molecule inhibitors of proteases and protease-like enzymes with various therapeutic applications. These molecules often comprise distinct structural moieties, so called warheads which mediate specific interactions with the target enzymes. Knowledge on the biosynthesis of the protease inhibitors warheads can be used to search for orphan pathways with similar capacities in bacterial genomes. The identified biosynthetic gene clusters likely encode the production of new protease inhibitors with the same mode of action as the template compound.
Bakterienprofile in natürlichen und technischen Ökosystemen(S. 46)
Burga Braun, Henrik Knecht, Sven Neulinger, Josephin Schröder, Ulrich Szewzyk
The increased use of xenobiotica has led to their accumulation in soils, water bodies and ground water as a result of insufficient removal by sewage plants. Bacteria are able to break down or transform a variety of chemicals due to the great diversity of their degradation pathways. Their occurrence and activity is an important research theme in environmental engineering. 16S amplicon and transcriptome sequencing are powerful tools to investigate the diversity and function of bacterial populations.
Anwendungen & Produkte
Massive Analysis of cDNA Ends (MACE): eine effektive RNA-Seq-Variante(S. 58)
Björn Rotter, Alejandro Rodriguez
With the massive analysis of cDNA ends (MACE) technology, a digital gene expression method combined with molecule identifiers (TrueQuant) becomes available, requiring only one read per transcript molecule. The sequencing depth can thereby be reduced by up to 90 percent to measure gene expression including rare transcripts. Because of a reduced sequenced area and its higher coverage with reads, MACE also has advantages for the analysis of allele specific gene expression, the identification of gene-polymorphisms and to measure alternative polyadenylation of transcripts.
Chemisch definiert – ein zellbasierter Zytotoxizitätsassay ohne fötales Kälberserum(S. 61)
Tests for cytotoxicity – respectively biocompatibility – are performed e. g. for biological evaluation of medical devices or during the development of microphysiometric systems. Here, often cell culture methods which involve the use of fetal bovine serum (FBS) are employed. However, using FBS raises scientific and ethical concerns. In the presented work a pro - tocol for a chemically defined test for cytotoxicity is described.
Immobilisierung von Enzymen: Spielerei oder biotechnologischer Fortschritt?(S. 95)
Michael Dreifke, Michael Fröba
The immobilization of enzymes is a widespread method to enhance their stability and especially to ensure reusability. To date a lot of porous and nonporous materials have attracted attention as possible enzyme hosts. Depending on the host material various methods were developed to bind an enzyme onto a carrier. Nowadays immobilized enzymes play an important role in the chemical industry and are employed in numerous fields.
Hydantoinasen – von der präbiotischen Evolution zur Aminosäureproduktion(S. 98)
Jens Rudat, Ulrike Engel
The hydantoinase process is used for the large-scale production of optically pure amino acids, with side chains of semisynthetic penicillins as the most prominent products. The origin as well as the natural function of the eponymous enzymes, however, remains unclear to this day. Here we discuss the way of hydantoinases from prebiotic evolution to directed evolution, spanning some billion years from the origin of life to industrial processes.