@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 = {Bacterial Bacterial_Proteins Blotting Deoxyribonuclease_I Electrophoresis Electrophoretic_Mobility_Shift_Assay Gene_Expression_Regulation Luciferases Northern Oxidation-Reduction Polyacrylamide_Gel Protein_Binding Rhodobacter_capsulatus Trans-Activators Two-Hybrid_System_Techniques}
}

@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 = {Bacterial Bacterial_Proteins DNA-Binding_Proteins Escherichia_coli Flavoproteins Gene_Expression_Regulation Light Microbial Oxidation-Reduction Oxygen Paracoccus_denitrificans Photoreceptors Photosynthesis Repressor_Proteins Rhodobacter_capsulatus Rhodobacter_sphaeroides Signal_Transduction Trans-Activators}
}