%0 Journal Article %1 han_haem_2007 %A Han, Yuchen %A Meyer, Martin H F %A Keusgen, Michael %A Klug, Gabriele %D 2007 %J Molecular microbiology %K Amino_Acid_Sequence Bacterial Bacterial_Proteins Biological Coenzymes DNA-Binding_Proteins Electrophoretic_Mobility_Shift_Assay Escherichia_coli Flavoproteins Gene_Expression_Regulation Heme Hemin IFZ Light Models Molecular_Sequence_Data Oxidation-Reduction Protein_Binding Protein_Structure Recombinant_Proteins Repressor_Proteins Rhodobacter_sphaeroides Sequence_Alignment Sequence_Deletion Signal_Transduction Spectrum_Analysis Tertiary %P 1090-104 %T A haem cofactor is required for redox and light signalling by the AppA protein of Rhodobacter sphaeroides %V 64 %X 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.

@article{han_haem_2007, 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.}, added-at = {2008-05-07T15:52:44.000+0200}, author = {Han, Yuchen and Meyer, Martin H F and Keusgen, Michael and Klug, Gabriele}, biburl = {https://www.bibsonomy.org/bibtex/24ac18fa9640073e4d8ca4eaa9746a5a4/mikromolbio}, interhash = {acdbc9477472342207d4ecab328ffd94}, intrahash = {4ac18fa9640073e4d8ca4eaa9746a5a4}, issn = {0950382}, journal = {Molecular microbiology}, keywords = {Amino_Acid_Sequence Bacterial Bacterial_Proteins Biological Coenzymes DNA-Binding_Proteins Electrophoretic_Mobility_Shift_Assay Escherichia_coli Flavoproteins Gene_Expression_Regulation Heme Hemin IFZ Light Models Molecular_Sequence_Data Oxidation-Reduction Protein_Binding Protein_Structure Recombinant_Proteins Repressor_Proteins Rhodobacter_sphaeroides Sequence_Alignment Sequence_Deletion Signal_Transduction Spectrum_Analysis Tertiary}, month = May, note = {PMID: 17501930}, pages = {1090-104}, timestamp = {2008-07-18T14:09:57.000+0200}, title = {A haem cofactor is required for redox and light signalling by the AppA protein of Rhodobacter sphaeroides}, volume = 64, year = 2007 }