4B3W: Crystal Structure Of Human Cytoglobin H(e7)q Mutant

Citation:
Abstract
Cytoglobin (Cygb) was recently discovered in the human genome and localized in different tissues. It was suggested to play tissue-specific protective roles, spanning from scavenging of reactive oxygen species in neurons to supplying oxygen to enzymes in fibroblasts. To shed light on the functioning of such versatile machinery, we have studied the processes supporting transport of gaseous heme ligands in Cygb. Carbon monoxide rebinding shows a complex kinetic pattern with several distinct reaction intermediates, reflecting rebinding from temporary docking sites, second order recombination, and formation (and dissociation) of a bis-histidyl heme hexacoordinated reaction intermediate. Ligand exit to the solvent occurs through distinct pathways, some of which exploit temporary docking sites. The remarkable change in energetic barriers, linked to heme bis-histidyl hexacoordination by HisE7, may be responsible for active regulation of the flux of reactants and products to and from the reaction site on the distal side of the heme. A substantial change in both protein dynamics and inner cavities is observed upon transition from the CO-liganded to the pentacoordinated and bis-histidyl hexacoordinated species, which could be exploited as a signalling state. These findings are consistent with the expected versatility of the molecular activity of this protein.
PDB ID: 4B3WDownload
MMDB ID: 106875
PDB Deposition Date: 2012/7/26
Updated in MMDB: 2013/01
Experimental Method:
x-ray diffraction
Resolution: 2.8  Å
Source Organism:
Similar Structures:
Biological Unit for 4B3W: dimeric; determined by author and by software (PISA)
Molecular Components in 4B3W
Label Count Molecule
Proteins (2 molecules)
2
Cytoglobin(Gene symbol: CYGB)
Molecule annotation
Chemicals (7 molecules)
1
2
2
2
3
2
4
1
* Click molecule labels to explore molecular sequence information.

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