91 research outputs found
From Stakeholder Management to Stakeholder Accountability
No full textConfronted with mounting pressure to ensure accountability vis-Ã -vis customers, citizens and beneficiaries, organizational leaders need to decide how to choose and implement so-called accountability standards. Yet while looking for an appropriate standard, they often base their decisions on cost-benefit calculations, thus neglecting other important spheres of influence pertaining to more broadly defined stakeholder interests. We argue in this paper that, as a part of the strategic decision for a certain standard, management needs to identify and act according to the needs of all stakeholders. We contend that the creation of a dialogical understanding among affected stakeholders cannot be a mere outcome of applying certain accountability standards, but rather must be a necessary precondition for their use. This requires a stakeholder dialogue prior to making a choice. We outline such a discursive decision framework for accountability standards based on the Habermasian concept of communicative action and, in the final section, apply our conceptual framework to one of the most prominent accountability tools (AA 1000). Copyright Springer 2006accountability standards, discourse ethics, Habermas, organizational accountability, stakeholder management, stakeholder dialogue,
Self-Assembled Hybrid Aptamer-Fc Conjugates for Targeted Delivery: A Modular Chemoenzymatic Approach
No full textOver the past decade, DNA and RNA aptamers have attracted keen research interest due to their ability to specifically bind targets of therapeutic relevance. However, their application is often hampered by a short serum half-life and missing effector functions. Conjugation of aptamers to antibody Fc fragments could improve pharmacokinetics, enable immune effector mechanisms, and provide an option for the introduction of desired payloads (e.g., toxins or fluorescent dyes). We developed a modular scaffold-supported system based on human IgG1 Fc fragments, which allows for its dual functionalization with moieties of interest. In our approach, two bioorthogonal, enzyme-mediated reactions were used in combination with oxime ligation and self-assembly based on PNA-DNA base pairing. Thus, an engineered synthetic peptide nucleic acid (PNA) oligomer was coupled to the C-termini of the Fc dimer upon sequence-specific sortase A-mediated transpeptidation. Hybridization of the resulting Fc-PNA conjugate with a tailored DNA aptamer that binds cancer-related hepatocyte growth factor receptor (c-MET) led to a hybrid construct which showed strong and specific binding to c-MET and was readily internalized by c-MET-overexpressing cells. To install an additional orthogonally addressable site, aldehyde tag technology was applied followed by oxime ligation with an aminooxy-bearing fluorescent dye as model cargo. Delivery of fluorescent probe specifically to c-MET-overexpressing cells was confirmed by flow cytometry. Our approach can provide access to engineered aptamer-Fc conjugates with desired target specificity and cytotoxic payloads.Merck Serono Innovation Cup initiative; Merck Serono Innovation Cu
135th Commencement Address
No full textThe 2024 commencement speaker, Stephen M. Rasche, J.D., was honored by the University with the Presidential Medal, with Dean Payne providing an introduction of Rasche’s career as an international authority on the displacement and persecution of religious minorities, a founding member of Catholic University in Erbil, Iraq, and author of the critically acclaimed book, The Disappearing People: The Tragic Fate of Christians in the Middle East.
In his commencement address, Rasche urged the graduates to remember there are “so many paths to take [...] to leverage this one life you have, to do the one thing that we are all ultimately called to do: that is, to serve.” He then reflected on the arc of his life and career that led him from practice in international project development to Iraq in the middle of a war to help a beleaguered Archbishop build a university from nothing, figuring out how to apply the many skills he had gained from his legal training to help take care of nearly 200,000 displaced human beings. In looking back on his work to protect the lives of those impacted by war and genocide, Rasche pointed to the “many fingerprints on all this work,” noting that “I can honestly say, and say it here, in this place, that down deep in those critical years, quite in the middle of it all, are the fingerprints of a lawyer, using all of his skills, however imperfectly, praying daily to God for guidance, so that he could use those skills in service for the good.
Crystal structure of Cwc2 reveals a novel architecture of a multipartite RNA-binding protein.
No full textThe yeast splicing factor Cwc2 contacts several catalytically important RNA elements in the active spliceosome, suggesting that Cwc2 is involved in determining their spatial arrangement at the spliceosome's catalytic centre. We have determined the crystal structure of the Cwc2 functional core, revealing how a previously uncharacterized Torus domain, an RNA recognition motif (RRM) and a zinc finger (ZnF) are tightly integrated in a compact folding unit. The ZnF plays a pivotal role in the architecture of the whole assembly. UV-induced crosslinking of Cwc2–U6 snRNA allowed the identification by mass spectrometry of six RNA-contacting sites: four in or close to the RRM domain, one in the ZnF and one on a protruding element connecting the Torus and RRM domains. The three distinct regions contacting RNA are connected by a contiguous and conserved positively charged surface, suggesting an expanded interface for RNA accommodation. Cwc2 mutations confirmed that the connector element plays a crucial role in splicing. We conclude that Cwc2 acts as a multipartite RNA-binding platform to bring RNA elements of the spliceosome's catalytic centre into an active conformation
Eine chemoenzymatische Kupplungsstrategie zur Immobilisierung von Proteinen auf kristalliner Nanocellulose
No full textA chemoenzymatic approach to protein immobilization onto crystalline cellulose nanoscaffolds
No full textThe immobilization of bioactive molecules onto nanocellulose leads to constructs that combine the properties of the grafted compounds with the biocompatibility and low cytotoxicity of cellulose carriers and the advantages given by their nanometer dimensions. However, the methods commonly used for protein grafting suffer from lack of selectivity, long reaction times, nonphysiological pH ranges and solvents, and the necessity to develop a tailor-made reaction strategy for each individual case. To overcome these restrictions, a generic two-step procedure was developed that takes advantage of the highly efficient oxime ligation combined with enzyme-mediated protein coupling onto the surface of peptide-modified crystalline nanocellulose. The described method is based on efficient and orthogonal transformations, requires no organic solvents, and takes place under physiological conditions. Being site-directed and regiospecific, it could be applied to a vast number of functional proteins.</p
Researching strategy practices: a genealogical social theory perspective
No full textThis paper explores the meaning and significance of the term `social practice' and its relation to strategy-as-practice research from the perspective of social theory. Although our remarks are also applicable to other practice-based discussions in management, we discuss strategy practices as a case in point and thus contribute to the strategy-as-practice literature in three ways. First, instead of simply accepting the existence of a unified `practice theory', we outline a genealogical analysis revealing the historical-contingent conditions of its creation. This analysis shows that social practices in general and strategy practices in particular can be approached from either a neo-structuralist and/or neo-interpretative perspective. Second, based on this theoretical argument, we discuss different characteristics of strategy practices and emphasize those aspects not yet fully considered by strategy-as-practice research (e.g. the physical nature of practices). Third, we show that, when studying strategy practices, given an understanding of the alternative theoretical approaches available, the practice of strategy research itself needs to be adjusted so as to accommodate a stronger emphasis on an ethnographic approach that is directed towards uncovering the contextual and hidden characteristics of strategy-making
Untersuchungen zum Mechanismus der katalytischen Aktivierung von Spleißosomen aus Saccharomyces Cerevisiae
No full textPre-mRNA splicing is catalyzed by the spliceosome, a multimegadalton ribonucleoprotein (RNP) complex. It assembles anew on each pre-mRNA intron by the stepwise binding of five snRNPs (U1, U2, U4, U5 and U6) and numerous proteins leading to the formation of the spliceosomal complex B which does not have yet an active catalytic site. For the establishment of the active site major structural changes are required, resulting in the formation of the activated B complex (Bact), which is then converted into the catalytically activated B* complex by the action of the Prp2 RNA helicase. Following the recruitment of the splicing factor Cwc25, the first step of splicing occurs, whereby the 5' splice site of the pre mRNA is cleaved and the 5' end of the intron is ligated to the branch site adenosine to form a lariat-like structure; concomitantly the C complex is formed. At this time the second step of splicing occurs which leads to exon ligation. The newly formed mRNP is released from the spliceosome and the intron lariat spliceosome is disassembled. The released snRNPs are thought to re-assemble for a new round of splicing.
A complex RNA–RNA network involving the snRNAs and the pre mRNA is formed during spliceosome assembly, and the resulting RNA structure plays a central role in catalysing the two steps of splicing. During spliceosome activation, U6 snRNA rearranges and forms an internal stem-loop (ISL) which plays a central role in the catalysis of splicing. The U6-ISL contains an internal bulge region that is critical for metal-ion binding and contains functionally important residues. U6 snRNA also forms base pairs with U2 snRNA generating the U2/U6 helix I. Finally, U6 snRNA via its conserved ACAGAGA sequence, also forms base pairs with the 5' end of the intron. In this arrangement, the branch site is juxtaposed with the 5' splice site.
While the importance of individual RNA-structural elements such as U6 ISL, U2/U6 helix I and the U6 ACAGAGA/5' splice site helix for splicing catalysis is well established, little was known at the time I started this work about how these various RNA elements are brought into a catalytically active tertiary conformation. Interestingly, if one examines how the catalytic center of the group II self-splicing introns is organized, a number of similarities between pre-mRNA and group II intron splicing can be recognized and indicate that the RNA elements of the respective catalytic core adopt similar folds in both systems. These include (i) the identical chemistry of the catalytic steps of both kinds of splicing and (ii) the great similarity between catalytically important structural elements in group II introns and the spliceosomal RNA network, especially between domain V (DV) of group II introns (which forms a stem-loop) and the U6 ISL, both of which bind catalytically active metal ions. One of the most impressive features revealed by the recently published crystal structure of an intact self-spliced group IIC intron is how numerous long-distance interactions between conserved structural elements of DI to VI and DV are essential to induce an unusual, catalytically important fold in DV.
In view of the paucity of conserved RNA tertiary structures in spliceosomal introns that might direct the folding and juxtaposition of essential catalytic RNA-structural elements (i.e U6 ISL and U2/U6 helix I) into an active conformation, it seems likely that spliceosomal proteins may have taken over this function, at least in part. Good candidates would be one or more of those proteins that become stably integrated into the spliceosome during its activation (i.e., the formation of the Bact complex). In yeast, these include a protein complex termed the “nineteen complex” (NTC) that consists of eight core proteins, and an additional set of NTC-related proteins. Among these, the yeast Cwc2 protein was of particular interest since it has an RRM and a zinc-finger domain, is essential for pre mRNA splicing in vivo and has been shown to contact U6 snRNA during splicing in yeast extracts.
Here we show that Cwc2 is essential for the first step of splicing in vitro, and that it is not required for the Prp2-mediated remodelling step that generates the catalytically competent B* complex. We demonstrate that in purified catalytically active spliceosomes, Cwc2 contacts the U6 ISL, as well as regions of the U6 snRNA and the intron adjacent to the 5' splice site. Chemical structure-probing further suggests that Cwc2 may also directly or indirectly contact U6/U2 helix I. Thus, our data place Cwc2 at the heart of the spliceosome's catalytic center. During this time the crystal structure of the Cwc2 functional core was solved by our group, and could be used to determine structure-function relationships by rational mutagenesis of Cwc2 combined with splicing. In addition, mass spectrometric analysis of RNA-protein crosslinks and electrophoretic mobility shift assays (EMSA) showed that Cwc2 acts as a multipartite RNA binding platform to bring RNA elements of the spliceosome’s catalytic center into an active conformation.
Interestingly, we also show that RNA interactions involving Cwc2 are evolutionarily conserved, as demonstrated by studies of its human counterpart RBM22, indicating that the observed Cwc2/RBM22 RNA contacts in the spliceosome are functionally important. We propose that Cwc2, in co operation with the essential splicing factor Prp8, induces an active conformation of the catalytic RNA elements in the spliceosome. In conclusion, our data suggest that the function of RNA-RNA tertiary interactions within group II introns, that is, to induce a catalytically active RNA conformation of DV, has probably been taken over by proteins that contact the functionally analogous U6-ISL, within the spliceosome
Aktuelle Rechtsprechung des Bundesgerichts im Gesellschaftsrecht – Teil 1
No full textIm Beitrag finden Sie eine Zusammenstellung von in der amtlichen Sammlung publizierten und weiteren wichtigen (nicht amtlich publizierten) Entscheiden des Bundesgerichts im Gesellschaftsrecht von Oktober 2016 bis Oktober 2017. Dem Praktiker soll damit eine rasche Übersicht über die Entwicklungen in der bundesgerichtlichen Rechtsprechung gegeben werden. Die Zusammenfassungen der Urteile sind mit Bemerkungen versehen.+ ID der Publikation: unilu_33680 + Sprache: Deutsch + Letzte Aktualisierung: 2018-07-04 16:19:5
Prp2-mediated protein rearrangements at the catalytic core of the spliceosome as revealed by dcFCCS.
No full textThe compositional and conformational changes during catalytic activation of the spliceosome promoted by the DEAH box ATPase Prp2 are only poorly understood. Here, we show by dual-color fluorescence cross-correlation spectroscopy (dcFCCS) that the binding affinity of several proteins is significantly changed during the Prp2-mediated transition of precatalytic Bact spliceosomes to catalytically activated B* spliceosomes from Saccharomyces cerevisiae. During this step, several proteins, including the zinc-finger protein Cwc24, are quantitatively displaced from the B* complex. Consistent with this, we show that Cwc24 is required for step 1 but not for catalysis per se. The U2-associated SF3a and SF3b proteins Prp11 and Cus1 remain bound to the B* spliceosome under near-physiological conditions, but their binding is reduced at high salt. Conversely, high-affinity binding sites are created for Yju2 and Cwc25 during catalytic activation, consistent with their requirement for step 1 catalysis. Our results suggest high cooperativity of multiple Prp2-mediated structural rearrangements at the spliceosome’s catalytic core. Moreover, dcFCCS represents a powerful tool ideally suited to study quantitatively spliceosomal protein dynamics in equilibrium
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