title: Crystal structures of the CO and NOBound DosS GAF-A domain and implications for DosS signaling in Mycobacterium tuberculosis.
abstract: DosS is a sensor in Mycobacterium tuberculosis that differentially responds to O2, NO, and CO, as well as to changes in the redox state of the prosthetic heme iron atom. The ferrous protein and its Fe(II)NO and Fe(II)CO complexes undergo autophosphorylation and subsequently transfer the phosphate group to DosR, a nuclear factor, to activate it. In contrast, autophosphorylation is negligible with the ferric protein and the Fe(II)O2complex. To clarify the basis for this differential response to gases, we have determined the crystal structures of the NO and COcomplexes of the DosS GAF-A domain, which contains the heme to which the gases bind. Comparison of these crystal structures with those reported for the phosphorylation-inactive ferric GAF-A domain suggest that the GAF-A domain is in a dynamic equilibrium between active and inactive states, and that the position of Glu87 in the heme cavity, which depends on the which gas is bound, acts as a modulator of the equilibrium, and therefore of catalytic activity.
authors.affiliation: Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143, United States.
authors.forename: Yarrow
authors.initials: Y
authors.lastname: Madrona
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143, United States.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Waddling
authors.affiliation: Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143, United States. Electronic address: ortiz@cgl.ucsf.edu.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Ortiz de Montellano
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry*; D002248:Carbon Monoxide / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D006418:Heme / Q000737:chemistry; D006860:Hydrogen Bonding; D007501:Iron / Q000737:chemistry*; D009169:Mycobacterium tuberculosis / Q000737:chemistry*; D009569:Nitric Oxide / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D010766:Phosphorylation; D006656:Protamine Kinase / Q000737:chemistry*; D000072417:Protein Domains; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D015398:Signal Transduction
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D009569:Nitric Oxide; D006418:Heme; D002248:Carbon Monoxide; D007501:Iron; C506260:DevS protein, Mycobacterium tuberculosis; D006656:Protamine Kinase; D010100:Oxygen
keywords: Conformational selection; DosS; Gas sensor; Hemoprotein; Mycobacterium tuberculosis; X-ray crystallography