Publications by authors named "Monika Nietschke"

, a foodborne and human pathogen, is a constant threat to human health. Agricultural environments, for example, soil and plants, can be ecological niches and vectors for transmission. persistence in such environments increases the risk for consumers.

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Effector molecules translocated by the Salmonella pathogenicity island (SPI)1-encoded type 3 secretion system (T3SS) critically contribute to the pathogenesis of human Salmonella infection. They facilitate internalization by non-phagocytic enterocytes rendering the intestinal epithelium an entry site for infection. Their function in vivo has remained ill-defined due to the lack of a suitable animal model that allows visualization of intraepithelial Salmonella.

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Research in cell biology demands advanced microscopy techniques such as confocal fluorescence microscopy (FM), super-resolution microscopy (SRM) and transmission electron microscopy (TEM). Correlative light and electron microscopy (CLEM) is an approach to combine data on the dynamics of proteins or protein complexes in living cells with the ultrastructural details in the low nanometre scale. To correlate both data sets, markers functional in FM, SRM and TEM are required.

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Transport of flagellar structural proteins beyond the cytoplasmic membrane is accomplished by a type III secretory pathway [flagellar type III secretion system (fTTSS)]. The mechanism of substrate recognition by the fTTSS is still enigmatic. Using the hook scaffolding protein FlgD of Escherichia coli as a model substrate, it is demonstrated that the export signal is contained within the N-terminal 71 amino acids of FlgD.

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Proximity relationships within three doubly spin-labeled variants of the Na+/proline transporter PutP of Escherichia coli were studied by means of four-pulse double electron-electron resonance spectroscopy. The large value of 4.8 nm for the interspin distance determined between positions 107 in loop 4 and 223 in loop 7 strongly supports the idea of these positions being located on opposite sides of the membrane.

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l-Carnitine is essential for beta-oxidation of fatty acids in mitochondria. Bacterial metabolic pathways are used for the production of this medically important compound. Here, we report the first detailed functional characterization of the caiT gene product, a putative transport protein whose function is required for l-carnitine conversion in Escherichia coli.

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To elucidate the functional importance of transmembrane domain II in the Na(+)/proline transporter (PutP) of Escherichia coli we analyzed the effect of replacing Ser-54 through Gly-58. Substitution of Asp-55 or Met-56 dramatically reduces the apparent affinity for Na(+) and Li(+) in a cation-dependent manner. Conversely, Cys in place of Gly-58 significantly reduces only the apparent proline affinity while substitution of Ser-57 results in a dramatic reduction of the apparent proline and cation affinities.

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