@article{BenzMaierBaueretal.2014,
  author    = {Benz, Roland and Maier, Elke and Bauer, Susanne and Ludwig, Albrecht},
  title     = {The Deletion of Several Amino Acid Stretches of Escherichia coli Alpha-Hemolysin (HlyA) Suggests That the Channel-Forming Domain Contains Beta-Strands},
  series = {PLOS ONE},
  volume    = {9},
  journal   = {PLOS ONE},
  number    = {12},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0112248},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-118115},
  pages     = {e112248},
  year      = {2014},
  abstract  = {Escherichia coli α-hemolysin (HlyA) is a pore-forming protein of 110 kDa belonging to the family of RTX toxins. A hydrophobic region between the amino acid residues 238 and 410 in the N-terminal half of HlyA has previously been suggested to form hydrophobic and/or amphipathic α-helices and has been shown to be important for hemolytic activity and pore formation in biological and artificial membranes. The structure of the HlyA transmembrane channel is, however, largely unknown. For further investigation of the channel structure, we deleted in HlyA different stretches of amino acids that could form amphipathic β-strands according to secondary structure predictions (residues 71-110, 158-167, 180-203, and 264-286). These deletions resulted in HlyA mutants with strongly reduced hemolytic activity. Lipid bilayer measurements demonstrated that HlyAΔ71-110 and HlyAΔ264-286 formed channels with much smaller single-channel conductance than wildtype HlyA, whereas their channel-forming activity was virtually as high as that of the wildtype toxin. HlyAΔ158-167 and HlyAΔ180-203 were unable to form defined channels in lipid bilayers. Calculations based on the single-channel data indicated that the channels generated by HlyAΔ71-110 and HlyAΔ264-286 had a smaller size (diameter about 1.4 to 1.8 nm) than wildtype HlyA channels (diameter about 2.0 to 2.6 nm), suggesting that in these mutants part of the channel-forming domain was removed. Osmotic protection experiments with erythrocytes confirmed that HlyA, HlyAΔ71-110, and HlyAΔ264-286 form defined transmembrane pores and suggested channel diameters that largely agreed with those estimated from the single-channel data. Taken together, these results suggest that the channel-forming domain of HlyA might contain β-strands, possibly in addition to α-helical structures.},
  language  = {en}
}
@article{SteinerZacharyBaueretal.2023,
  author    = {Steiner, Thomas and Zachary, Marie and Bauer, Susanne and M{\"u}ller, Martin J. and Krischke, Markus and Radziej, Sandra and Klepsch, Maximilian and Huettel, Bruno and Eisenreich, Wolfgang and Rudel, Thomas and Beier, Dagmar},
  title     = {Central Role of Sibling Small RNAs NgncR_162 and NgncR_163 in Main Metabolic Pathways of Neisseria gonorrhoeae},
  series = {mBio},
  volume    = {14},
  journal   = {mBio},
  doi       = {10.1128/mbio.03093-22},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-313323},
  year      = {2023},
  abstract  = {Small bacterial regulatory RNAs (sRNAs) have been implicated in the regulation of numerous metabolic pathways. In most of these studies, sRNA-dependent regulation of mRNAs or proteins of enzymes in metabolic pathways has been predicted to affect the metabolism of these bacteria. However, only in a very few cases has the role in metabolism been demonstrated. Here, we performed a combined transcriptome and metabolome analysis to define the regulon of the sibling sRNAs NgncR_162 and NgncR_163 (NgncR_162/163) and their impact on the metabolism of Neisseria gonorrhoeae. These sRNAs have been reported to control genes of the citric acid and methylcitric acid cycles by posttranscriptional negative regulation. By transcriptome analysis, we now expand the NgncR_162/163 regulon by several new members and provide evidence that the sibling sRNAs act as both negative and positive regulators of target gene expression. Newly identified NgncR_162/163 targets are mostly involved in transport processes, especially in the uptake of glycine, phenylalanine, and branched-chain amino acids. NgncR_162/163 also play key roles in the control of serine-glycine metabolism and, hence, probably affect biosyntheses of nucleotides, vitamins, and other amino acids via the supply of one-carbon (C\(_1\)) units. Indeed, these roles were confirmed by metabolomics and metabolic flux analysis, which revealed a bipartite metabolic network with glucose degradation for the supply of anabolic pathways and the usage of amino acids via the citric acid cycle for energy metabolism. Thus, by combined deep RNA sequencing (RNA-seq) and metabolomics, we significantly extended the regulon of NgncR_162/163 and demonstrated the role of NgncR_162/163 in the regulation of central metabolic pathways of the gonococcus.},
  language  = {en}
}