Technical University of Dortmund

About: Technical University of Dortmund is a education organization based out in Dortmund, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Large Hadron Collider & Neutrino. The organization has 13028 authors who have published 27666 publications receiving 615557 citations. The organization is also known as: Dortmund University & University of Dortmund.

Orthogonal Protein Decoration of DNA Origami

Abstract: Structural DNA nanotechnology 2] and the technique of DNA origami enable the rapid generation of a plethora of complex self-assembled nanostructures. Since DNA molecules themselves display limited chemical, optical, and electronic functionality, it is of utmost importance to devise methods to decorate DNA scaffolds with functional moieties to realize applications in sensing, catalysis, and device fabrication. Protein functionalization is particulary desirable because it allows exploitation of an almost unlimited variety of functional elements which nature has evolved over billions of years. The delicate architecture of proteins has resulted in no generally applicable method being currently available to selectively couple these components on DNA scaffolds, and thus approaches used so far are based on reversible antibody– antigen interactions, 9] aptamer binding, 11] nucleic acid hybridization of DNA-tagged proteins, 13] or predominantly biotin–streptavidin (STV) interactions. We demonstrate here that DNA nanostructures can be site-specifically decorated with several different proteins by using coupling systems orthogonal to the biotin–STV system. In particular, benzylguanine (BG) and chlorohexane (CH) groups incorporated in DNA origami have been used as suicide ligands for the site-specific coupling of fusion proteins containing the self-labeling protein tags O-alkylguanine-DNA-alkyltransferase (hAGT), which is often referred to as “Snap-tag”, or haloalkane dehalogenase, which is also known as “HaloTag”. By using various model proteins we demonstrate the general applicability of this approach for the generation of DNA superstructures that are selectively decorated with multiple different proteins. To realize orthogonal protein immobilization on DNA origami using self-ligating protein tags, we chose the Snap-tag, developed by Johnsson and co-workers, and the commercially available HaloTag system. The respective smallmolecule suicide tags (O-benzylguanine (BG) and 5-chlorohexane (CH)) for both self-labeling protein tags are readily available as amino-reactive N-hydroxysuccinimide (NHS) derivatives (BG-NHS and CH-NHS; Figure 1a). Complete derivatization of alkylamino-modified oligonucleotides was achieved by coupling with 30 molar equivalents of BG-NHS or CH-NHS, as indicated by electrophoretic analysis (Figure 1b). To gain access to fusion proteins bearing the complementary Snapand Halo-protein tags, we constructed expression plasmids by genetic fusion of the genes encoding the protein of interest (POI) and Snap-tag or HaloTag (see the Supporting Information). As model POIs we chose the fluorescent proteins enhanced yellow fluorescent protein (EYFP) and mKate, the enzymes cytochrome C peroxidase (CCP) and esterase 2 from Alicyclobacillus acidocaldarius thermos (EST2), to which the self-labeling tags were fused at the C terminus (POI-Snap or POI-Halo, respectively). In addition, the bispecific Halo-Snap fusion protein “covalin”, a chimera which specifically reacts with both BG and CH, as well as monovalent STV (mSTV), were used in this study. The fusion proteins were overexpressed and purified by conventional procedures (see the Supporting Information). The coupling of BGand CHmodified oligonucleotides to the protein was analyzed by using covalin as the initial model to simplify the electrophoretic characterization. It is shown in Figure 1c that both BGand CH-modified single-stranded DNA (ssDNA) oligonucleotides couple effectively to generate the corresponding DNA–covalin conjugates in nearly quantitative yields. DNA coupling of the aforementioned POI fusions, namely mKateSnap, EST2-SNAP, mKate-Halo, CCP-Halo, and EYFP-Halo occurred in a highly specific manner (Figure 1d), and neither Snap or Halo nor mSTV revealed cross-reactivity for the orthogonal-tagged DNA oligomers. We then used SARSE software to aid in the design of face-shaped DNA origami to demonstrate the selective immobilization of protein on DNA nanostructures. Correct folding of M13mp18 ssDNA through the use of 236 staple strands was analyzed by atomic force microscopy (AFM; details of the sequence design as well as experimental procedures are reported in the Supporting Information). Figure 2a illustrates that the face-shaped DNA origami was obtained in high purity, and high-resolution AFM clearly revealed the proposed ears, neck, and seam features of this structure. As an initial test for protein decoration, we selected 23 staple strands, which were biotinylated to create eyes (2 6 [*] Dr. B. Sacc , Dipl.-Chem. R. Meyer, Dipl.-Biotechnol. M. Erkelenz, M. Sc. K. Kiko, A. Arndt, Dr. H. Schroeder, Dr. K. S. Rabe, Prof. C. M. Niemeyer Technische Universit t Dortmund, Fakult t Chemie Biologisch-Chemische Mikrostrukturtechnik Otto-Hahn Strasse 6, 44227 Dortmund (Germany) Fax: (+ 49)231-755-7082 E-mail: christof.niemeyer@tu-dortmund.de [] These authors contributed equally to this work.

Work motivation, organisational identification, and well-being in call centre work

Abstract: Previous work has not considered the interplay of motivational forces linked to the task with those linked to the social identity of employees. The aim of the present study is to combine these approaches. Two studies with call centre agents (N=211, N=161) were conducted in which the relationships of objective working conditions (e.g., inbound vs. outbound work), subjective measures of motivating potential of work, and organisational identification were analysed. Job satisfaction, turnover intentions, organisational citizenship behavior (OCB), health complaints, and burnout were assessed as indicators of the agents’ work motivation and well-being. In both studies it was found that objective working conditions substantially correlated with subjective measures of work motivation. Moreover, employees experiencing a high motivating potential at work reported more OCB, higher job satisfaction, and less turnover intentions. As hypothesized, organisational identification was a further independent predict...

A Shape‐Adaptive, Antibacterial‐Coating of Immobilized Quaternary‐Ammonium Compounds Tethered on Hyperbranched Polyurea and its Mechanism of Action

Abstract: Quaternary-ammonium-compounds are potent cationic antimicrobials used in everyday consumer products. Surface-immobilized, quaternary-ammonium-compounds create an antimicrobial contact-killing coating. We describe the preparation of a shape-adaptive, contact-killing coating by tethering quaternary-ammonium-compounds onto hyperbranched polyurea coatings, able to kill adhering bacteria by partially enveloping them. Even after extensive washing, coatings caused high contact-killing of Staphylococcus epidermidis, both in culture-based assays and through confocal-laser-scanning-microscopic examination of the membrane-damage of adhering bacteria. In culture-based assays, at a challenge of 1600 CFU/cm(2), contact-killing was >99.99%. The working-mechanism of dissolved quaternary-ammonium-compounds is based on their interdigitation in bacterial membranes, but it is difficult to envisage how immobilized quaternary-ammonium-molecules can exert such a mechanism of action. Staphylococcal adhesion forces to hyperbranched quaternary-ammonium coatings were extremely high, indicating that quaternary-ammonium-molecules on hyperbranched polyurea partially envelope adhering bacteria upon contact. These lethally strong adhesion forces upon adhering bacteria then cause removal of membrane lipids and eventually lead to bacterial death.