Rational Design of Novel Peptidic DnaK Ligands
Max Planck Research Unit for Enzymology of Protein Folding, Weinbergweg 22, 06120 Halle-Saale, Germany.ChemBioChem (Impact Factor: 3.09). 08/2010; 11(12):1727-37. DOI: 10.1002/cbic.201000166
The hsp70 chaperone DnaK from E. coli plays a major role in cellular stress response and is involved in assisted protein folding in vivo. By screening a combinatorial peptide library, we identified several DnaK-specific peptide ligands with nanomolar affinities, which are able to inhibit the secondary amide peptide bond cis/trans isomerase (APIase) activity of DnaK, as well as DnaK/DnaJ/GrpE-assisted refolding of firefly luciferase. Our designed DnaK inhibitors have the capability to penetrate E. coli cells and feature a high protease resistance. Once inside the cell, they physically target DnaK. NMR-based (1)H/(15)N-HSQC experiments furthermore confirmed that the designed peptidic ligands all bind in an identical manner to the conventional peptide-binding site of DnaK. The subsequent blocking of DnaK function apparently results in the observed antibacterial effects on E. coli cells, with minimum inhibitory concentrations in the range of 100 microM.
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ABSTRACT: It is asserted that designers and developers of products repeatedly make the same mistakes in developing new products or modifying older products for the marketplace. The major deficiency is one of not analyzing the elements of a system to identify safety-related design concepts, functions, or interfaces with other system components. The interface should include all personnel coming in contact with the product and the eventual end user of the product. The major conclusion which can be drawn from experience is that a very practical process of analysis in which a single analysis applied to each system element and then to the system as a whole will identify the hazards of the design, the functioning of the product, and the human interface. This analysis is relatively inexpensive to perform. The payback to the product developer is better public relations, less expense due to litigation and subsequent insurance increases, less risk of outlay of funds, and a higher, long-range return on development funds expended through increased salesReliability and Maintainability Symposium, 1991. Proceedings., Annual; 03/1991
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ABSTRACT: The proline-rich antimicrobial peptide oncocin is remarkably active in vitro against a number of important Gram-negative bacteria of concern to humans owing to their increasing resistance to antibiotics, i.e. Enterobacteriaceae (Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae) and non-fermenting species (Acinetobacter baumannii and Pseudomonas aeruginosa). Degradation of oncocin in mouse serum was investigated in this study. Several approaches to stabilise the main cleavage sites (C-terminal to Arg-15 and N-terminal to Arg-19) by substituting either or both arginine (Arg) residues with non-proteinogenic amino acids, i.e. α-amino-3-guanidino-propionic acid, homoarginine, nitro-arginine, N-methyl-arginine, β-homoarginine, D-arginine (D-Arg) or ornithine (Orn), were tested. These modifications were found to increase the half-life of oncocin in full mouse serum. For oncocin with two Orn residues in positions 15 and 19, the half-life in full serum increased from 25 min to 3 h. An increase of >8 h was observed for oncocin with two D-Arg residues at these same positions. The antibacterial activities of these modified sequences were slightly better than the original oncocin sequence. Moreover, the three most stable analogues were found to be bactericidal against E. coli and were not toxic to HeLa cells or haemolytic to human erythrocytes.International journal of antimicrobial agents 02/2011; 37(2):166-70. DOI:10.1016/j.ijantimicag.2010.10.028 · 4.30 Impact Factor
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