4HH1: Dark-state structure of AppA wild-type without the Cys-rich region from Rb. sphaeroides

The 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.
PDB ID: 4HH1Download
MMDB ID: 110696
PDB Deposition Date: 2012/10/9
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 3.501  Å
Source Organism:
Similar Structures:
Biological Unit for 4HH1: monomeric; determined by author
Molecular Components in 4HH1
Label Count Molecule
Protein (1 molecule)
Appa Protein
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

Citing MMDB