@article{AbdaKrysciakKrohnMoltetal.2015,
  author    = {Abda, Ebrahim M. and Krysciak, Dagmar and Krohn-Molt, Ines and Mamat, Uwe and Schmeisser, Christel and F{\"o}rstner, Konrad U. and Schaible, Ulrich E. and Kohi, Thomas A. and Nieman, Stefan and Streit, Wolfgang R.},
  title     = {Phenotypic Heterogeneity Affects Stenotrophomonas maltophilia K279a Colony Morphotypes and \(\beta\)-Lactamase Expression},
  series = {Frontiers in Microbiology},
  volume    = {6},
  journal   = {Frontiers in Microbiology},
  number    = {1373},
  doi       = {10.3389/fmicb.2015.01373},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-136446},
  year      = {2015},
  abstract  = {Phenotypic heterogeneity at the cellular level in response to various stresses, e.g., antibiotic treatment has been reported for a number of bacteria. In a clonal population, cell-to-cell variation may result in phenotypic heterogeneity that is a mechanism to survive changing environments including antibiotic therapy. Stenotrophomonas rnaltophilia has been frequently isolated from cystic fibrosis patients, can cause numerous infections in other organs and tissues, and is difficult to treat due to antibiotic resistances. S. maltophilia K279a produces the Li and L2 beta-lactamases in response to beta-lactam treatment. Here we report that the patient isolate S. rnaltophilia K279a diverges into cellular subpopulations with distinct but reversible morphotypes of small and big colonies when challenged with ampicillin. This observation is consistent with the formation of elongated chains of bacteria during exponential growth phase and the occurrence of mainly rod-shaped cells in liquid media. RNA-seq analysis of small versus big colonies revealed differential regulation of at least seven genes among the colony morphotypes. Among those, bleu and bla(L2) were transcriptionally the most strongly upregulated genes. Promoter fusions of b/a(L1) and b/a(L2) genes indicated that expression of both genes is also subject to high levels of phenotypic heterogeneous expression on a single cell level. Additionally, the comE homolog was found to be differentially expressed in homogenously versus heterogeneously bla(L2) expressing cells as identified by RNA(seq) analysis. Overexpression of cornE in S. maltophilia K279a reduced the level of cells that were in a bla(L2)-ON mode to 1\% or lower. Taken together, our data provide strong evidence that S. maltophilia K279a populations develop phenotypic heterogeneity in an ampicillin challenged model. This cellular variability is triggered by regulation networks including b/a(L1), b/a(L2), and comE.},
  language  = {en}
}
@article{HerwegHansmeierOttoetal.2015,
  author    = {Herweg, Jo-Ana and Hansmeier, Nicole and Otto, Andreas and Geffken, Anna C. and Subbarayal, Prema and Prusty, Bhupesh K. and Becher, D{\"o}rte and Hensel, Michael and Schaible, Ulrich E. and Rudel, Thomas and Hilbi, Hubert},
  title     = {Purification and proteomics of pathogen-modified vacuoles and membranes},
  series = {Frontiers in Cellular and Infection Microbiology},
  volume    = {5},
  journal   = {Frontiers in Cellular and Infection Microbiology},
  number    = {48},
  doi       = {10.3389/fcimb.2015.00048},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-151823},
  year      = {2015},
  abstract  = {Certain pathogenic bacteria adopt an intracellular lifestyle and proliferate in eukaryotic host cells. The intracellular niche protects the bacteria from cellular and humoral components of the mammalian immune system, and at the same time, allows the bacteria to gain access to otherwise restricted nutrient sources. Yet, intracellular protection and access to nutrients comes with a price, i.e., the bacteria need to overcome cell-autonomous defense mechanisms, such as the bactericidal endocytic pathway. While a few bacteria rupture the early phagosome and escape into the host cytoplasm, most intracellular pathogens form a distinct, degradation-resistant and replication-permissive membranous compartment. Intracellular bacteria that form unique pathogen vacuoles include Legionella, Mycobacterium, Chlamydia, Simkania, and Salmonella species. In order to understand the formation of these pathogen niches on a global scale and in a comprehensive and quantitative manner, an inventory of compartment-associated host factors is required. To this end, the intact pathogen compartments need to be isolated, purified and biochemically characterized. Here, we review recent progress on the isolation and purification of pathogen-modified vacuoles and membranes, as well as their proteomic characterization by mass spectrometry and different validation approaches. These studies provide the basis for further investigations on the specific mechanisms of pathogen-driven compartment formation.},
  language  = {en}
}