Central role of Tim17 in mitochondrial presequence protein translocation.

The presequence translocase of the mitochondrial inner membrane (TIM23) represents the major route for the import of nuclear-encoded proteins into mitochondria1,2. About 60% of more than 1,000 different mitochondrial proteins are synthesized with amino-terminal targeting signals, termed presequences, which form positively charged amphiphilic α-helices3,4. TIM23 sorts the presequence proteins into the inner membrane or matrix. Various views, including regulatory and coupling functions, have been reported on the essential TIM23 subunit Tim17 (refs. 5-7). Here we mapped the interaction of Tim17 with matrix-targeted and inner membrane-sorted preproteins during translocation in the native membrane environment. We show that Tim17 contains conserved negative charges close to the intermembrane space side of the bilayer, which are essential to initiate presequence protein translocation along a distinct transmembrane cavity of Tim17 for both classes of preproteins. The amphiphilic character of mitochondrial presequences directly matches this Tim17-dependent translocation mechanism. This mechanism permits direct lateral release of transmembrane segments of inner membrane-sorted precursors into the inner membrane.

Establishing an Interoperable Clinical Trial Information System Within MIRACUM.

In the long-run we wish to demonstrate the power of linking clinical trial information to routine health records for straightforward patient recruitment - not only at each single hospital but in a large German consortium (called MIRACUM). In such architecture a hospital wide clinical trial registry (CTR) plays a major role. All such site specific CTR however, also need to be interoperable and support automated data provision for a central MIRACUM wide trial registry. Based on a survey of already existing trial information systems at each partner site and a comparison of their functionality, a joint requirement specification was created, a minimal MIRACUM wide trial core dataset was defined and an architecture was designed in which each MIRACUM partner could keep their autonomous system decision. Partners could however also join forces in a cooperative enhancement of a new open source trial registry. Thus, sites with no trial registry could be supported by the others and synergies used. Finally, the newly developed CTR will allow modular site specific add-ons and can also take over the function of the MIRACUM wide trial registry. In this paper we describe the process, how such a consortium-wide CTR was designed and developed, while always keeping cross-site interoperability as a major requirement.

The German Clinical Trials Register: challenges and chances of implementing a bilingual registry.

OBJECTIVE: It is a moral responsibility towards patients, funding organizations, the scientific community and the general public to publish not only the results of clinical trials but also to inform prospectively about planned trials. This is especially important for scientists, funding organizations, and ethics committees, since they are involved in the planning of new trials, which should rely on the knowledge of existing trials. Moreover, patients can only participate in clinical trials if they or their physicians are aware of ongoing trials for which they are eligible. In order to provide a central portal for information on clinical research in Germany and to facilitate the search for specific trials, the German Clinical Trials Register was implemented in 2008. METHOD: An internet-based prototype of the German Clinical Trials Register was developed in close co-operation with the World Health Organization's registries network on the basis of the internationally harmonized data specification. This was further adapted to a bilingual registry's needs. Co-operation with medical ethics committees in Germany has been initiated with the aim of a joint synergistic data acquisition procedure. RESULTS: The German Clinical Trials Register was launched in August 2008. It was approved as the World Health Organization's primary registry for Germany in October 2008, and fulfils the requirements of the International Committee of Journal Editors. CONCLUSION: The German Clinical Trials Register provides a central bilingual portal for all users (including scientists, patients, physicians, funding organizations, and ethics committees) for information on planned, ongoing, and completed clinical trials conducted in Germany. The German Clinical Trials Register allows International Committee of Journal Editors and World Health Organization-compliant registration of clinical trials in Germany.

Regulation of the sigmaE stress response by DegS: how the PDZ domain keeps the protease inactive in the resting state and allows integration of different OMP-derived stress signals upon folding stress.

The unfolded protein response of Escherichia coli is triggered by the accumulation of unassembled outer membrane proteins (OMPs) in the cellular envelope. The PDZ-protease DegS recognizes these mislocalized OMPs and initiates a proteolytic cascade that ultimately leads to the sigmaE-driven expression of a variety of factors dealing with folding stress in the periplasm and OMP assembly. The general features of how OMPs activate the protease function of DegS have not yet been systematically addressed. Furthermore, it is unknown how the PDZ domain keeps the protease inactive in the resting state, which is of crucial importance for the functioning of the entire sigmaE stress response. Here we show in atomic detail how DegS is able to integrate the information of distinct stress signals that originate from different OMPs containing a -x-Phe C-terminal motif. A dedicated loop of the protease domain, loop L3, serves as a versatile sensor for allosteric ligands. L3 is capable of interacting differently with ligands but reorients in a conserved manner to activate DegS. Our data also indicate that the PDZ domain directly inhibits protease function in the absence of stress signals by wedging loop L3 in a conformation that ultimately disrupts the proteolytic site. Thus, the PDZ domain and loop L3 of DegS define a novel molecular switch allowing strict regulation of the sigmaE stress response system.