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 11.3 angstrom 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.

Nardini, M., Pesce, A., Thijs, L., Saito, J., Dewilde, S., Alam, M., et al. (2008). Archaeal protoglobin structure indicates new ligand diffusion paths and modulation of haem-reactivity. EMBO REPORTS, 9(2), 157-163 [10.1038/sj.embor.7401153].

Archaeal protoglobin structure indicates new ligand diffusion paths and modulation of haem-reactivity

COLETTA, MASSIMILIANO;
2008-01-01

Abstract

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 11.3 angstrom 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.
2008
Pubblicato
Rilevanza internazionale
Articolo
Sì, ma tipo non specificato
Settore BIO/10 - BIOCHIMICA
English
bacterial protein; carbon dioxide; cytoglobin; globin; hemoglobin; hemoprotein; matrix protein; neuroglobin; nitric oxide; oxygen; protoglobin; amino terminal sequence; article; crystal structure; ligand binding; Methanosarcina; Methanosarcina acetivorans; molecular cloning; mutagenesis; nonhuman; nucleotide sequence; priority journal; protein determination; protein expression; protein family; protein function; protein localization; protein structure; Archaeal Proteins; Carbon Monoxide; Crystallography, X-Ray; Diffusion; Heme; Kinetics; Ligands; Methanosarcina; Models, Molecular; Oxygen; Protein Structure, Secondary; Thermodynamics; Archaea; Methanosarcina acetivorans
Nardini, M., Pesce, A., Thijs, L., Saito, J., Dewilde, S., Alam, M., et al. (2008). Archaeal protoglobin structure indicates new ligand diffusion paths and modulation of haem-reactivity. EMBO REPORTS, 9(2), 157-163 [10.1038/sj.embor.7401153].
Nardini, M; Pesce, A; Thijs, L; Saito, J; Dewilde, S; Alam, M; Ascenzi, P; Coletta, M; Ciaccio, C; Moens, L; Bolognesi, M
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/41168
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