Ultrafast Ligand Dynamics in the Heme-Based GAF Sensor Domains of the Histidine Kinases DosS and DosT from Mycobacterium tuberculosis. - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Biochemistry Année : 2012

Ultrafast Ligand Dynamics in the Heme-Based GAF Sensor Domains of the Histidine Kinases DosS and DosT from Mycobacterium tuberculosis.

Marten H. Vos
Hao Luo
  • Fonction : Auteur
Julian J. Eaton-Rye
  • Fonction : Auteur
Alexandra Ioanoviciu
  • Fonction : Auteur
Paul Ortiz de Montellano
  • Fonction : Auteur
Ursula Liebl
  • Fonction : Auteur
  • PersonId : 864658

Résumé

The transcriptional regulator DosR from M. tuberculosis plays a crucial role in the virulence to dormancy transition of the pathogen. DosR can be activated by DosT and DosS, two histidine kinases with heme-containing sensor GAF domains, capable of diatomic ligand binding. To investigate the initial processes occurring upon ligand dissociation, we performed ultrafast time-resolved absorption spectroscopy of the isolated sensor domains ligated with O2, NO, and CO. The results reveal a relatively closed heme pocket for both proteins. For DosT the yield of O2 escape from the heme pocket on the picoseconds time scale upon photodissociation was found to be very low (1.5%), similar to other heme-based oxygen sensor proteins, implying that this sensor acts as an effective O2 trap. Remarkably, this yield is an order of magnitude higher in DosS (18%). For CO, by contrast, the fraction of CO rebinding within the heme pocket is higher in DosS. Experiments with mutant DosT sensor domains and molecular dynamics simulations indicate an important role in ligand discrimination of the distal tyrosine, present in both proteins, which forms a hydrogen bond with heme-bound O2. We conclude that despite their similarity, DosT and DosS display ligand-specific different primary dynamics during the initial phases of intraprotein signaling. The distal tyrosine, present in both proteins, plays an important role in these processes.

Dates et versions

hal-00097195 , version 1 (21-09-2006)

Identifiants

Citer

Marten H. Vos, Latifa Bouzhir-Sima, Jean-Christophe Lambry, Hao Luo, Julian J. Eaton-Rye, et al.. Ultrafast Ligand Dynamics in the Heme-Based GAF Sensor Domains of the Histidine Kinases DosS and DosT from Mycobacterium tuberculosis.. Biochemistry, 2012, 51 (1), pp.159-166. ⟨10.1021/bi201467c⟩. ⟨hal-00097195⟩
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