@article{MakbulKraftGriessmannetal.2021,
  author    = {Makbul, Cihan and Kraft, Christian and Grießmann, Matthias and Rasmussen, Tim and Katzenberger, Kilian and Lappe, Melina and Pfarr, Paul and Stoffer, Cato and St{\"o}hr, Mara and Wandinger, Anna-Maria and B{\"o}ttcher, Bettina},
  title     = {Binding of a pocket factor to Hepatitis B virus capsids changes the rotamer conformation of Phenylalanine 97},
  series = {Viruses},
  volume    = {13},
  journal   = {Viruses},
  number    = {11},
  issn      = {1999-4915},
  doi       = {10.3390/v13112115},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-248565},
  year      = {2021},
  abstract  = {(1) Background: During maturation of the Hepatitis B virus, a viral polymerase inside the capsid transcribes a pre-genomic RNA into a partly double stranded DNA-genome. This is followed by envelopment with surface proteins inserted into a membrane. Envelopment is hypothetically regulated by a structural signal that reports the maturation state of the genome. NMR data suggest that such a signal can be mimicked by the binding of the detergent Triton X 100 to hydrophobic pockets in the capsid spikes. (2) Methods: We have used electron cryo-microscopy and image processing to elucidate the structural changes that are concomitant with the binding of Triton X 100. (3) Results: Our maps show that Triton X 100 binds with its hydrophobic head group inside the pocket. The hydrophilic tail delineates the outside of the spike and is coordinated via Lys-96. The binding of Triton X 100 changes the rotamer conformation of Phe-97 in helix 4, which enables a π-stacking interaction with Trp-62 in helix 3. Similar changes occur in mutants with low secretion phenotypes (P5T and L60V) and in a mutant with a pre-mature secretion phenotype (F97L). (4) Conclusion: Binding of Triton X 100 is unlikely to mimic structural maturation because mutants with different secretion phenotypes show similar structural responses.},
  language  = {en}
}
@article{Rasmussen2023,
  author    = {Rasmussen, Tim},
  title     = {The potassium efflux system Kef: bacterial protection against toxic electrophilic compounds},
  series = {Membranes},
  volume    = {13},
  journal   = {Membranes},
  number    = {5},
  issn      = {2077-0375},
  doi       = {10.3390/membranes13050465},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-313686},
  year      = {2023},
  abstract  = {Kef couples the potassium efflux with proton influx in gram-negative bacteria. The resulting acidification of the cytosol efficiently prevents the killing of the bacteria by reactive electrophilic compounds. While other degradation pathways for electrophiles exist, Kef is a short-term response that is crucial for survival. It requires tight regulation since its activation comes with the burden of disturbed homeostasis. Electrophiles, entering the cell, react spontaneously or catalytically with glutathione, which is present at high concentrations in the cytosol. The resulting glutathione conjugates bind to the cytosolic regulatory domain of Kef and trigger activation while the binding of glutathione keeps the system closed. Furthermore, nucleotides can bind to this domain for stabilization or inhibition. The binding of an additional ancillary subunit, called KefF or KefG, to the cytosolic domain is required for full activation. The regulatory domain is termed K+ transport-nucleotide binding (KTN) or regulator of potassium conductance (RCK) domain, and it is also found in potassium uptake systems or channels in other oligomeric arrangements. Bacterial RosB-like transporters and K+ efflux antiporters (KEA) of plants are homologs of Kef but fulfill different functions. In summary, Kef provides an interesting and well-studied example of a highly regulated bacterial transport system.},
  language  = {en}
}