PMID:14982921
| Citation |
Kurokawa, H, Lee, DS, Watanabe, M, Sagami, I, Mikami, B, Raman, CS and Shimizu, T (2004) A redox-controlled molecular switch revealed by the crystal structure of a bacterial heme PAS sensor. J. Biol. Chem. 279:20186-93 |
|---|---|
| Abstract |
PAS domains, which have been identified in over 1100 proteins from all three kingdoms of life, convert various input stimuli into signals that propagate to downstream components by modifying protein-protein interactions. One such protein is the Escherichia coli redox sensor, Ec DOS, a phosphodiesterase that degrades cyclic adenosine monophosphate in a redox-dependent manner. Here we report the crystal structures of the heme PAS domain of Ec DOS in both inactive Fe(3+) and active Fe(2+) forms at 1.32 and 1.9 A resolution, respectively. The protein folds into a characteristic PAS domain structure and forms a homodimer. In the Fe(3+) form, the heme iron is ligated to a His-77 side chain and a water molecule. Heme iron reduction is accompanied by heme-ligand switching from the water molecule to a side chain of Met-95 from the FG loop. Concomitantly, the flexible FG loop is significantly rigidified, along with a change in the hydrogen bonding pattern and rotation of subunits relative to each other. The present data led us to propose a novel redox-regulated molecular switch in which local heme-ligand switching may trigger a global "scissor-type" subunit movement that facilitates catalytic control. |
| Links |
PubMed Online version:10.1074/jbc.M314199200 |
| Keywords |
Amino Acid Sequence; Carrier Proteins/chemistry; Catalysis; Crystallography, X-Ray; Cyclic AMP/metabolism; Dimerization; Escherichia coli/metabolism; Escherichia coli Proteins/chemistry; Heme/chemistry; Hydrogen Bonding; Iron/chemistry; Ligands; Methionine/chemistry; Models, Molecular; Molecular Sequence Data; Oxidation-Reduction; Phosphoric Diester Hydrolases; Protein Folding; Protein Structure, Tertiary; Sequence Homology, Amino Acid |
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