4hh0
Dark-state structure of AppA C20S without the Cys-rich region from Rb. sphaeroidesDark-state structure of AppA C20S without the Cys-rich region from Rb. sphaeroides
Structural highlights
Publication Abstract from PubMedThe anoxygenic phototrophic bacterium Rhodobacter sphaeroides uses different energy sources, depending on environmental conditions including aerobic respiration or, in the absence of oxygen, photosynthesis. Photosynthetic genes are repressed at high oxygen tension, but at intermediate levels their partial expression prepares the bacterium for using light energy. Illumination, however, enhances repression under semiaerobic conditions. Here, we describe molecular details of two proteins mediating oxygen and light control of photosynthesis-gene expression: the light-sensing antirepressor AppA and the transcriptional repressor PpsR. Our crystal structures of both proteins and their complex and hydrogen/deuterium-exchange data show that light activation of AppA-PpsR2 affects the PpsR effector region within the complex. DNA binding studies demonstrate the formation of a light-sensitive ternary AppA-PpsR-DNA complex. We discuss implications of these results for regulation by light and oxygen, highlighting new insights into blue light-mediated signal transduction. A ternary AppA-PpsR-DNA complex mediates light regulation of photosynthesis-related gene expression.,Winkler A, Heintz U, Lindner R, Reinstein J, Shoeman RL, Schlichting I Nat Struct Mol Biol. 2013 Jul;20(7):859-67. doi: 10.1038/nsmb.2597. Epub 2013 Jun, 2. PMID:23728293[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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