Thorsten W Grebe

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Signal transduction in microorganisms and plants is often mediated by His-Asp phosphorelay systems. Two conserved families of proteins are centrally involved: histidine protein kinases and phospho-aspartyl response regulators. The kinases generally function in association with sensory elements that regulate their activities in response to environmental(More)
Motor behavior in prokaryotes is regulated by a phosphorelay network involving a histidine protein kinase, CheA, whose activity is controlled by a family of Type I membrane receptors. In a typical Escherichia coli cell, several thousand receptors are organized together with CheA and an Src homology 3-like protein, CheW, into complexes that tend to be(More)
The beta-lactams are by far the most widely used and efficacious of all antibiotics. Over the past few decades, however, widespread resistance has evolved among most common pathogens. Streptococcus pneumoniae has become a paradigm for understanding the evolution of resistance mechanisms, the simplest of which, by far, is the production of beta-lactamases.(More)
Piperacillin resistance in Streptococcus pneumoniae was mediated by mutations in a novel gene, cpoA, that also confer transformation deficiency and a decrease in penicillin-binding protein la. cpoA is part of an operon located downstream of the primary sigma factor of S. pneumoniae. The deduced protein, CpoA, and the peptide encoded by the adjacent 3' open(More)
High-level resistance to beta-lactam antibiotics in Streptococcus pneumoniae is mediated by successive alterations in essential penicillin-binding proteins (PBPs). In the present work, single amino acid changes in S. pneumoniae PBP 2x and PBP 2b that result in reduced affinity for the antibiotic and that confer first-level beta-lactam resistance are(More)
Laboratory mutants of Streptococcus pneumoniae resistant to either cefotaxime or piperacillin reveal defects in competence development independent of the selective beta-lactam. A resistance determinant ciaH encoding a putative histidine kinase of a two-component signal-transducing system that is also involved in competence regulation was recently identified(More)
In Streptococcus pneumoniae, alterations in penicillin-binding protein 2b (PBP 2b) that reduce the affinity for penicillin binding are observed during development of beta-lactam resistance. The development of resistance was now studied in three independently obtained piperacillin-resistant laboratory mutants isolated after several selection steps on(More)
Different penicillin-binding proteins PBPs are affected in cefotaxime-resistant laboratory mutants compared to piperacillin-resistant mutants. PBP2x acts as the primary PBP target in cefotaxime-resistant mutants, whereas PBP2b is the primary target in piperacillin-resistant mutants. Depending on the mutations in PBP2x, it functions as a resistance(More)
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