2VEB image
Entry Detail
PDB ID:
2VEB
Title:
High resolution structure of protoglobin from Methanosarcina acetivorans C2A
Biological Source:
Host Organism:
PDB Version:
Deposition Date:
2007-10-18
Release Date:
2008-01-22
Method Details:
Experimental Method:
Resolution:
1.30 Å
R-Value Free:
0.19
R-Value Work:
0.16
R-Value Observed:
0.16
Space Group:
C 1 2 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:PROTOGLOBIN
Mutations:YES
Chain IDs:A
Chain Length:195
Number of Molecules:1
Biological Source:METHANOSARCINA ACETIVORANS
Primary Citation
Archaeal Protoglobin Structure Indicates New Ligand Diffusion Paths and Modulation of Haem-Reactivity.
Embo Rep. 9 157 ? (2008)
PMID: 18188182 DOI: 10.1038/SJ.EMBOR.7401153

Abstact

The structural adaptability of the globin fold has been highlighted by the recent discovery of the 2-on-2 haemoglobins, of neuroglobin and cytoglobin. Protoglobin from Methanosarcina acetivorans C2A-a strictly anaerobic methanogenic Archaea-is, to the best of our knowledge, the latest entry adding new variability and functional complexity to the haemoglobin (Hb) superfamily. Here, we report the 1.3 A crystal structure of oxygenated M. acetivorans protoglobin, together with the first insight into its ligand-binding properties. We show that, contrary to all known globins, protoglobin-specific loops and an amino-terminal extension completely bury the haem within the protein matrix. Access of O(2), CO and NO to the haem is granted by the protoglobin-specific apolar tunnels reaching the haem distal site from locations at the B/G and B/E helix interfaces. Functionally, M. acetivorans dimeric protoglobin shows a selectivity ratio for O(2)/CO binding to the haem that favours O(2) ligation and anticooperativity in ligand binding. Both properties are exceptional within the Hb superfamily.

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