Bettina Kempf

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All microorganisms possess a positive turgor, and maintenance of this outward-directed pressure is essential since it is generally considered as the driving force for cell expansion. Exposure of microorganisms to high-osmolality environments triggers rapid fluxes of cell water along the osmotic gradient out of the cell, thus causing a reduction in turgor(More)
Exogenously provided glycine betaine can efficiently protect Bacillus subtilis from the detrimental effects of high osmolarity environments. Through functional complementation of an Escherichia coli mutant deficient in glycine betaine uptake with a gene library from B. subtilis, we have identified a multicomponent glycine betaine transport system, OpuA.(More)
The Escherichia coli hns gene encodes the abundant nucleoid-associated DNA-binding protein H-NS. Mutations in hns alter the expression of many genes with unrelated functions and result in a derepression of the proU operon (proVWX) without abolishing the osmotic control of its transcription. We have investigated the interactions of H-NS with the proU(More)
The accumulation of the osmoprotectant glycine betaine from exogenous sources provides a high degree of osmotic tolerance to Bacillus subtilis. We have identified, through functional complementation of an Escherichia coli mutant defective in glycine betaine uptake, a new glycine betaine transport system from B. subtilis. The DNA sequence of a 2,310-bp(More)
The ProP and ProU transport systems of Escherichia coli mediate the uptake of several osmoprotectants including glycine betaine. Here we report that both ProP and ProU are involved in the transport of the potent osmoprotectant proline betaine. A set of isogenic E. coli strains carrying deletions in either the proP or proU loci was constructed. The growth(More)
Exogenously provided glycine betaine functions as an efficient osmoprotectant for Bacillus subtilis in high-osmolarity environments. This gram-positive soil organism is not able to increase the intracellular level of glycine betaine through de novo synthesis in defined medium (A. M. Whatmore, J. A. Chudek, and R. H. Reed, J. Gen. Microbiol. 136:2527-2535,(More)
Biosynthesis of the compatible solute glycine betaine in Bacillus subtilis confers a considerable degree of osmotic tolerance and proceeds via a two-step oxidation process of choline, with glycine betaine aldehyde as the intermediate. We have exploited the sensitivity of B. subtilis strains defective in glycine betaine production against glycine betaine(More)
Synthesis of the osmoprotectant glycine betaine from the exogenously provided precursor choline or glycine betaine aldehyde confers considerable osmotic stress tolerance to Bacillus subtilis in high-osmolarity media. Using an Escherichia coli mutant (betBA) defective in the glycine betaine synthesis enzymes, we cloned by functional complementation the genes(More)
Exogenously provided proline has been shown to serve as an osmoprotectant in Bacillus subtilis. Uptake of proline is under osmotic control and functions independently of the known transport systems for the osmoprotectant glycine betaine. We cloned the structural gene (opuE) for this proline transport system and constructed a chromosomal opuE mutant by(More)
In pemphigus vulgaris, a life-threatening autoimmune skin disease, epidermal blisters are caused by autoantibodies primarily targeting desmosomal cadherins desmoglein 3 (DSG3) and DSG1, leading to loss of keratinocyte cohesion. Due to limited insights into disease pathogenesis, current therapy relies primarily on nonspecific long-term immunosuppression.(More)