@article{BerghoffKonzerManketal.2013,
  author    = {Berghoff, Bork A. and Konzer, Anne and Mank, Nils N. and Looso, Mario and Rische, Tom and F{\"o}rstner, Konrad U. and Kr{\"u}ger, Marcus and Klug, Gabriele},
  title     = {Integrative "Omics"-Approach Discovers Dynamic and Regulatory Features of Bacterial Stress Responses},
  series = {PLOS Genetics},
  volume    = {9},
  journal   = {PLOS Genetics},
  number    = {6},
  issn      = {1553-7404},
  doi       = {10.1371/journal.pgen.1003576},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-127587},
  pages     = {e1003576},
  year      = {2013},
  abstract  = {Bacteria constantly face stress conditions and therefore mount specific responses to ensure adaptation and survival. Stress responses were believed to be predominantly regulated at the transcriptional level. In the phototrophic bacterium Rhodobacter sphaeroides the response to singlet oxygen is initiated by alternative sigma factors. Further adaptive mechanisms include post-transcriptional and post-translational events, which have to be considered to gain a deeper understanding of how sophisticated regulation networks operate. To address this issue, we integrated three layers of regulation: (1) total mRNA levels at different time-points revealed dynamics of the transcriptome, (2) mRNAs in polysome fractions reported on translational regulation (translatome), and (3) SILAC-based mass spectrometry was used to quantify protein abundances (proteome). The singlet oxygen stress response exhibited highly dynamic features regarding short-term effects and late adaptation, which could in part be assigned to the sigma factors RpoE and RpoH2 generating distinct expression kinetics of corresponding regulons. The occurrence of polar expression patterns of genes within stress-inducible operons pointed to an alternative of dynamic fine-tuning upon stress. In addition to transcriptional activation, we observed significant induction of genes at the post-transcriptional level (translatome), which identified new putative regulators and assigned genes of quorum sensing to the singlet oxygen stress response. Intriguingly, the SILAC approach explored the stress-dependent decline of photosynthetic proteins, but also identified 19 new open reading frames, which were partly validated by RNA-seq. We propose that comparative approaches as presented here will help to create multi-layered expression maps on the system level ("expressome"). Finally, intense mass spectrometry combined with RNA-seq might be the future tool of choice to re-annotate genomes in various organisms and will help to understand how they adapt to alternating conditions.},
  language  = {en}
}
@article{RemesBerghoffFoerstneretal.2014,
  author    = {Remes, Bernhard and Berghoff, Bork A. and F{\"o}rstner, Konrad U. and Klug, Gabriele},
  title     = {Role of oxygen and the OxyR protein in the response to iron limitation in Rhodobacter sphaeroides},
  series = {BMC Genomics},
  volume    = {15},
  journal   = {BMC Genomics},
  number    = {794},
  issn      = {1471-2164},
  doi       = {10.1186/1471-2164-15-794},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-115357},
  year      = {2014},
  abstract  = {Background: High intracellular levels of unbound iron can contribute to the production of reactive oxygen species (ROS) via the Fenton reaction, while depletion of iron limits the availability of iron-containing proteins, some of which have important functions in defence against oxidative stress. Vice versa increased ROS levels lead to the damage of proteins with iron sulphur centres. Thus, organisms have to coordinate and balance their responses to oxidative stress and iron availability. Our knowledge of the molecular mechanisms underlying the co-regulation of these responses remains limited. To discriminate between a direct cellular response to iron limitation and indirect responses, which are the consequence of increased levels of ROS, we compared the response of the alpha-proteobacterium Rhodobacter sphaeroides to iron limitation in the presence or absence of oxygen. Results: One third of all genes with altered expression under iron limitation showed a response that was independent of oxygen availability. The other iron-regulated genes showed different responses in oxic or anoxic conditions and were grouped into six clusters based on the different expression profiles. For two of these clusters, induction in response to iron limitation under oxic conditions was dependent on the OxyR regulatory protein. An OxyR mutant showed increased ROS production and impaired growth under iron limitation. Conclusion: Some R. sphaeroides genes respond to iron limitation irrespective of oxygen availability. These genes therefore reflect a "core iron response" that is independent of potential ROS production under oxic, iron-limiting conditions. However, the regulation of most of the iron-responsive genes was biased by oxygen availability. Most strikingly, the OxyR-dependent activation of a subset of genes upon iron limitation under oxic conditions, including many genes with a role in iron metabolism, revealed that elevated ROS levels were an important trigger for this response. OxyR thus provides a regulatory link between the responses to oxidative stress and to iron limitation in R. sphaeroides.},
  language  = {en}
}
@article{FoerstnerReuscherHaberzettletal.2018,
  author    = {F{\"o}rstner, Konrad U and Reuscher, Carina M and Haberzettl, Kerstin and Weber, Lennart and Klug, Gabriele},
  title     = {RNase E cleavage shapes the transcriptome of Rhodobacter sphaeroides and strongly impacts phototrophic growth},
  series = {Life Science Alliance},
  volume    = {1},
  journal   = {Life Science Alliance},
  number    = {4},
  doi       = {10.26508/lsa.201800080},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177139},
  pages     = {e201800080},
  year      = {2018},
  abstract  = {Bacteria adapt to changing environmental conditions by rapid changes in their transcriptome. This is achieved not only by adjusting rates of transcription but also by processing and degradation of RNAs. We applied TIER-Seq (transiently inactivating an endoribonuclease followed by RNA-Seq) for the transcriptome-wide identification of RNase E cleavage sites and of 5′ RNA ends, which are enriched when RNase E activity is reduced in Rhodobacter sphaeroides. These results reveal the importance of RNase E for the maturation and turnover of mRNAs, rRNAs, and sRNAs in this guanine-cytosine-rich α-proteobacterium, some of the latter have well-described functions in the oxidative stress response. In agreement with this, a role of RNase E in the oxidative stress response is demonstrated. A remarkably strong phenotype of a mutant with reduced RNase E activity was observed regarding the formation of photosynthetic complexes and phototrophic growth, whereas there was no effect on chemotrophic growth.},
  language  = {en}
}