@article{glaeser_protein_2007, title = {Protein synthesis patterns reveal a complex regulatory response to singlet oxygen in Rhodobacter}, author = {Jens Glaeser and Monica Zobawa and Friedrich Lottspeich and Gabriele Klug}, journal = {Journal of proteome research}, month = {July}, note = {PMID: 17536848}, pages = {2460-71}, volume = 6, year = 2007, issn = {15353893}, abstract = {Singlet oxygen (1O2) is a stress factor and signal in the facultative phototrophic bacterium Rhodobacter sphaeroides. In vivo protein labeling with L-[35S]-methionine and analysis by two-dimensional gel electrophoresis revealed that the synthesis of 61 proteins was changed in response to 1O2. After 1O2 treatment, protein synthesis patterns were distinct from those after H2O2 treatment but similar to those after high light exposure. This indicates regulatory mechanisms selective for different reactive oxygen species (ROS) and a response to light partly mediated by 1O2. Analysis of mutant strains support that the response to 1O2 is regulated mainly by rpoE (sigma E), but also a modulation of the sigma E dependent response by other factors and the existence of sigma E independent responses. The involvement of the RNA chaperon Hfq in the 1O2 response implies a role of small regulatory RNAs.}, biburl = {http://www.bibsonomy.org/bibtex/27ffd100e93e552721654848a86efd795/mikromolbio}, keywords = {Bacterial Protein_Biosynthesis Sigma_Factor Host_Factor_1_Protein Gene_Expression_Regulation Rhodobacter_sphaeroides Transcription_Factors Hydrogen_Peroxide Proteome Bacterial_Proteins Divalent Gel Light RNA Mutation Reactive_Oxygen_Species Two-Dimensional Singlet_Oxygen Cations Electrophoresis Messenger Catalase} } @article{gregor_bacterial_2007, title = {Bacterial regulatory networks include direct contact of response regulator proteins: interaction of RegA and NtrX in Rhodobacter capsulatus}, author = {Jutta Gregor and Tanja Zeller and Angelika Balzer and Kerstin Haberzettl and Gabriele Klug}, journal = {Journal of molecular microbiology and biotechnology}, note = {PMID: 17693720}, pages = {126-39}, volume = 13, year = 2007, issn = {14641801}, abstract = {The formation of photosynthetic complexes in facultatively photosynthetic bacteria is controlled by the oxygen tension in the environment. In Rhodobacter capsulatus the two-component system RegB/RegA plays a major role in the redox control of photosynthesis genes but also controls other redox-dependent systems. The response regulator RegA is phosphorylated under low oxygen tension and activates the puf and puc operons, which encode pigment binding proteins, by binding to their promoter regions. Data from a yeast two-hybrid analysis as well as an in vitroanalysis indicate that RegA interacts with the NtrX protein, the response regulator of the NtrY/NtrX two-component system which is believed to be involved in regulation of nitrogen fixation genes. Our further analysis revealed that NtrX is indeed involved in the regulation of the puf and puc operons. Furthermore, we showed that an altered NtrX protein, which is predicted to adopt the conformation of phosphorylated NtrX protein, binds within the puf promoter region close to the RegA binding sites. We conclude that a direct interaction of two response regulators connects the regulatory systems for redox control and nitrogen control.}, biburl = {http://www.bibsonomy.org/bibtex/2192438d916f82e78d51d7cfdd8031f65/mikromolbio}, keywords = {Electrophoresis Polyacrylamide_Gel Gene_Expression_Regulation Trans-Activators Oxidation-Reduction Electrophoretic_Mobility_Shift_Assay Bacterial Protein_Binding Northern Two-Hybrid_System_Techniques Blotting Deoxyribonuclease_I Luciferases Bacterial_Proteins Rhodobacter_capsulatus} } @article{han_haem_2007, title = {A haem cofactor is required for redox and light signalling by the AppA protein of Rhodobacter sphaeroides}, author = {Yuchen Han and Martin H F Meyer and Michael Keusgen and Gabriele Klug}, journal = {Molecular microbiology}, month = {May}, note = {PMID: 17501930}, pages = {1090-104}, volume = 64, year = 2007, issn = {0950382}, abstract = {The AppA protein of Rhodobacter sphaeroides is unique in its ability to sense and transmit redox signals as well as light signals. By functioning as antagonist to the PpsR transcriptional repressor, it regulates the expression of photosynthesis genes in response to these environmental stimuli. Here we show binding of the cofactor haem to a domain in the C-terminal part of AppA and redox activity of bound haem. This is supported by the findings that: (i) the C-terminal domain of AppA (AppADeltaN) binds to haemin agarose, (ii) AppADeltaN isolated from Escherichia coli shows absorbance at 411 nm and absorbances at 424 nm and 556 nm after reduction with dithionite and (iii) AppADeltaN can be reconstituted with haem in vitro. Expression of AppA variants in R. sphaeroides reveals that the haem binding domain is important for normal expression levels of photosynthesis genes and for normal light regulation in the presence of oxygen. The haem cofactor affects the interaction of the C-terminal part of AppA to PpsR but also its interaction to the N-terminal light sensing AppA-BLUF domain. Based on this we present a model for the transmission of light and redox signals by AppA.}, biburl = {http://www.bibsonomy.org/bibtex/24ac18fa9640073e4d8ca4eaa9746a5a4/mikromolbio}, keywords = {Coenzymes Protein_Structure Electrophoretic_Mobility_Shift_Assay Gene_Expression_Regulation Oxidation-Reduction Flavoproteins Protein_Binding Signal_Transduction Hemin Repressor_Proteins Escherichia_coli Amino_Acid_Sequence Bacterial Rhodobacter_sphaeroides Molecular_Sequence_Data Sequence_Deletion Spectrum_Analysis Recombinant_Proteins Bacterial_Proteins Light Biological Sequence_Alignment Tertiary Models Heme DNA-Binding_Proteins} } @article{hendrischk_phra_2007, title = {The phrA gene of Rhodobacter sphaeroides encodes a photolyase and is regulated by singlet oxygen and peroxide in a sigma(E)-dependent manner}, author = {Anne-Kathrin Hendrischk and Stephan Braatsch and Jens Glaeser and Gabriele Klug}, journal = {Microbiology (Reading, England)}, month = {June}, note = {PMID: 17526841}, pages = {1842-51}, volume = 153, year = 2007, issn = {13500872}, abstract = {The genome of the facultatively photosynthetic bacterium Rhodobacter sphaeroides encodes three proteins of the photolyase/cryptochrome family. This paper shows that phrA (RSP2143) encodes a functional photolyase, which is an enzyme that repairs UV radiation-induced DNA damage in a blue light dependent manner. Expression of phrA is upregulated in response to light, with no photoreceptor or the photosynthetic electron transport being involved. The results reveal that singlet oxygen and hydrogen peroxide dependent signals are transmitted by the sigma(E) factor and the anti-sigma(E) factor ChrR affecting phrA expression, while superoxide anions do not stimulate phrA expression. Thus, the sigma(E) regulon is involved not only in the response to singlet oxygen but also in the hydrogen peroxide response.}, biburl = {http://www.bibsonomy.org/bibtex/2f1831a18a9ee9dba81778273d45463ab/mikromolbio}, keywords = {Sequence_Alignment Anti-Bacterial_Agents Light Bacterial_Proteins beta-Galactosidase Deoxyribodipyrimidine_Photo-Lyase Microbial_Viability Singlet_Oxygen Up-Regulation Sigma_Factor Bacterial Rhodobacter_sphaeroides Peroxides Gene_Expression_Regulation Transcription_Factors Artificial_Gene_Fusion Reporter Molecular_Sequence_Data Superoxides Amino_Acid_Sequence Genes} } @article{jger_appa_2007, title = {The AppA and PpsR proteins from Rhodobacter sphaeroides can establish a redox-dependent signal chain but fail to transmit blue-light signals in other bacteria}, author = {Andreas Jäger and Stephan Braatsch and Kerstin Haberzettl and Sebastian Metz and Lisa Osterloh and Yuchen Han and Gabriele Klug}, journal = {Journal of bacteriology}, month = {March}, note = {PMID: 17209035}, pages = {2274-82}, volume = 189, year = 2007, issn = {00219193}, abstract = {The AppA protein of Rhodobacter sphaeroides has the unique ability to sense and transmit redox and light signals. In response to decreasing oxygen tension, AppA antagonizes the transcriptional regulator PpsR, which represses the expression of photosynthesis genes, including the puc operon. This mechanism, which is based on direct protein-protein interaction, is prevented by blue-light absorption of the BLUF domain located in the N-terminal part of AppA. In order to test whether AppA and PpsR are sufficient to transmit redox and light signals, we expressed these proteins in three different bacterial species and monitored oxygen- and blue-light-dependent puc expression either directly or by using a luciferase-based reporter construct. The AppA/PpsR system could mediate redox-dependent gene expression in the alphaproteobacteria Rhodobacter capsulatus and Paracoccus denitrificans but not in the gammaproteobacterium Escherichia coli. Analysis of a prrA mutant strain of R. sphaeroides strongly suggests that light-dependent gene expression requires a balanced interplay of the AppA/PpsR system with the PrrA response regulator. Therefore, the AppA/PpsR system was unable to establish light signaling in other bacteria. Based on our data, we present a model for the interdependence of AppA/PpsR signaling and the PrrA transcriptional activator.}, biburl = {http://www.bibsonomy.org/bibtex/2d09486188bc04d8a07c7ef5a470fbac6/mikromolbio}, keywords = {Gene_Expression_Regulation Photosynthesis Microbial Repressor_Proteins Signal_Transduction Rhodobacter_sphaeroides DNA-Binding_Proteins Rhodobacter_capsulatus Bacterial Oxygen Photoreceptors Paracoccus_denitrificans Oxidation-Reduction Bacterial_Proteins Escherichia_coli Flavoproteins Trans-Activators Light} }