6OTD

Globin sensor domain of AfGcHK in monomeric form, with imidazole

Summary for 6OTD

• Entry DOI: 10.2210/pdb6otd/pdb
• Related: 5OHE 5OHF
• Descriptor: Globin-coupled histidine kinase, PROTOPORPHYRIN IX CONTAINING FE, (4S)-2-METHYL-2,4-PENTANEDIOL, ... (5 entities in total)
• Functional Keywords: heme, sensor protein, oxygen sensor, globin sensor domain, globin domain, transferase, imidazole
• Biological source: Anaeromyxobacter sp. Fw109-5
• Total number of polymer chains: 1
• Total formula weight: 19243.69

Authors

Skalova, T.,Dohnalek, J.,Kolenko, P.,Stranava, M.,Lengalova, A.,Martinkova, M. (deposition date: 2019-05-03, release date: 2020-01-08, Last modification date: 2023-10-11)

Primary citation

Skalova, T.,Lengalova, A.,Dohnalek, J.,Harlos, K.,Mihalcin, P.,Kolenko, P.,Stranava, M.,Blaha, J.,Shimizu, T.,Martinkova, M.
Disruption of the dimerization interface of the sensing domain in the dimeric heme-based oxygen sensorAfGcHK abolishes bacterial signal transduction.
J.Biol.Chem., 295:1587-1597, 2020

PubMed Abstract: The heme-based oxygen sensor protein GcHK is a globin-coupled histidine kinase in the soil bacterium sp. Fw109-5. Its C-terminal functional domain exhibits autophosphorylation activity induced by oxygen binding to the heme-Fe(II) complex located in the oxygen-sensing N-terminal globin domain. A detailed understanding of the signal transduction mechanisms in heme-containing sensor proteins remains elusive. Here, we investigated the role of the globin domain's dimerization interface in signal transduction in GcHK. We present a crystal structure of a monomeric imidazole-bound GcHK globin domain at 1.8 Å resolution, revealing that the helices of the WT globin dimer are under tension and suggesting that Tyr-15 plays a role in both this tension and the globin domain's dimerization. Biophysical experiments revealed that whereas the isolated WT globin domain is dimeric in solution, the Y15A and Y15G variants in which Tyr-15 is replaced with Ala or Gly, respectively, are monomeric. Additionally, we found that although the dimerization of the full-length protein is preserved via the kinase domain dimerization interface in all variants, full-length GcHK variants bearing the Y15A or Y15G substitutions lack enzymatic activity. The combined structural and biophysical results presented here indicate that Tyr-15 plays a key role in the dimerization of the globin domain of GcHK and that globin domain dimerization is essential for internal signal transduction and autophosphorylation in this protein. These findings provide critical insights into the signal transduction mechanism of the histidine kinase GcHK from .

PubMed: 31914416
DOI: 10.1074/jbc.RA119.011574

Experimental method

X-RAY DIFFRACTION (1.8 Å)