5OHF

Globin sensor domain of AfGcHK (FeIII form) in complex with cyanide, partially reduced

Summary for 5OHF

• Entry DOI: 10.2210/pdb5ohf/pdb
• Descriptor: Globin-coupled histidine kinase, PROTOPORPHYRIN IX CONTAINING FE, CYANIDE ION, ... (6 entities in total)
• Functional Keywords: heme, sensor protein, oxygen sensor, globin sensor domain, globin domain, cyanide, transferase
• Biological source: Anaeromyxobacter sp. (strain Fw109-5)
• Total number of polymer chains: 8
• Total formula weight: 152307.18

Authors

Skalova, T.,Kolenko, P.,Dohnalek, J.,Stranava, M.,Martinkova, M. (deposition date: 2017-07-16, release date: 2017-11-08, Last modification date: 2024-01-17)

Primary citation

Stranava, M.,Man, P.,Skalova, T.,Kolenko, P.,Blaha, J.,Fojtikova, V.,Martinek, V.,Dohnalek, J.,Lengalova, A.,Rosulek, M.,Shimizu, T.,Martinkova, M.
Coordination and redox state-dependent structural changes of the heme-based oxygen sensor AfGcHK associated with intraprotein signal transduction.
J. Biol. Chem., 292:20921-20935, 2017

PubMed Abstract: The heme-based oxygen sensor histidine kinase GcHK is part of a two-component signal transduction system in bacteria. O binding to the Fe(II) heme complex of its N-terminal globin domain strongly stimulates autophosphorylation at His in its C-terminal kinase domain. The 6-coordinate heme Fe(III)-OH and -CN complexes of GcHK are also active, but the 5-coordinate heme Fe(II) complex and the heme-free apo-form are inactive. Here, we determined the crystal structures of the isolated dimeric globin domains of the active Fe(III)-CN and inactive 5-coordinate Fe(II) forms, revealing striking structural differences on the heme-proximal side of the globin domain. Using hydrogen/deuterium exchange coupled with mass spectrometry to characterize the conformations of the active and inactive forms of full-length GcHK in solution, we investigated the intramolecular signal transduction mechanisms. Major differences between the active and inactive forms were observed on the heme-proximal side (helix H5), at the dimerization interface (helices H6 and H7 and loop L7) of the globin domain and in the ATP-binding site (helices H9 and H11) of the kinase domain. Moreover, separation of the sensor and kinase domains, which deactivates catalysis, increased the solvent exposure of the globin domain-dimerization interface (helix H6) as well as the flexibility and solvent exposure of helix H11. Together, these results suggest that structural changes at the heme-proximal side, the globin domain-dimerization interface, and the ATP-binding site are important in the signal transduction mechanism of GcHK. We conclude that GcHK functions as an ensemble of molecules sampling at least two conformational states.

PubMed: 29092908
DOI: 10.1074/jbc.M117.817023

Experimental method

X-RAY DIFFRACTION (1.8 Å)