1v9y
Crystal Structure of the heme PAS sensor domain of Ec DOS (ferric form)
Structural highlights
FunctionDOSP_ECOLI Heme-based oxygen sensor protein displaying phosphodiesterase (PDE) activity toward c-di-GMP in response to oxygen availability. Involved in the modulation of intracellular c-di-GMP levels, in association with DosC which catalyzes the biosynthesis of c-di-GMP (diguanylate cyclase activity). Cyclic-di-GMP is a second messenger which controls cell surface-associated traits in bacteria. Has very poor PDE activity on cAMP (PubMed:15995192) but is not active with cGMP, bis(p-nitrophenyl) phosphate or p-nitrophenyl phosphate (PubMed:11970957). Via its PDE activity on c-di-GMP, DosP regulates biofilm formation through the repression of transcription of the csgBAC operon, which encodes curli structural subunits.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedPAS 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. A redox-controlled molecular switch revealed by the crystal structure of a bacterial heme PAS sensor.,Kurokawa H, Lee DS, Watanabe M, Sagami I, Mikami B, Raman CS, Shimizu T J Biol Chem. 2004 May 7;279(19):20186-93. Epub 2004 Feb 23. PMID:14982921[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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