3QZZ image
Entry Detail
PDB ID:
3QZZ
Title:
3D Structure of Ferric Methanosarcina Acetivorans Protoglobin Y61W mutant in Aquomet form
Biological Source:
Host Organism:
PDB Version:
Deposition Date:
2011-03-07
Release Date:
2011-06-08
Method Details:
Experimental Method:
Resolution:
2.40 Å
R-Value Free:
0.30
R-Value Work:
0.23
R-Value Observed:
0.24
Space Group:
C 1 2 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Methanosarcina acetivorans protoglobin
Mutations:C101S, Y61W
Chain IDs:A
Chain Length:195
Number of Molecules:1
Biological Source:Methanosarcina acetivorans
Ligand Molecules
Primary Citation
Structural heterogeneity and ligand gating in ferric methanosarcina acetivorans protoglobin mutants.
Iubmb Life 63 287 294 (2011)
PMID: 21618401 DOI: 10.1002/iub.484

Abstact

Protoglobin from Methanosarcina acetivorans C2A (MaPgb), a strictly anaerobic methanogenic Archaea, displays peculiar structural and functional properties within members of the hemoglobin superfamily. In fact, MaPgb-specific loops and a N-terminal extension (20 amino acid residues) completely bury the heme within the protein matrix. Therefore, the access of diatomic gaseous molecules to the heme is granted by two apolar tunnels reaching the heme distal site from locations at the B/G and B/E helix interfaces. The presence of two tunnels within the protein matrix could be partly responsible for the slightly biphasic ligand binding behavior. Unusually, MaPgb oxygenation is favored with respect to carbonylation. Here, the crucial role of Tyr(B10)61 and Ile(G11)149 residues, located in the heme distal site and lining the protein matrix tunnels 1 and 2, respectively, on ligand binding to the heme-Fe-atom and on distal site structural organization is reported. In particular, tunnel 1 accessibility is modulated by a complex reorganization of the Trp(B9)60 and Phe(E11)93 side-chains, triggered by mutations of the Tyr(B10)61 and Ile(G11)149 residues, and affected by the presence and type of the distal heme-bound ligand.

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