Archaeal protoglobin structure indicates new ligand diffusion paths and modulation of haem reactivity
Articolo
Data di Pubblicazione:
2008
Citazione:
Archaeal protoglobin structure indicates new ligand diffusion paths and modulation of haem reactivity / M. Nardini, A. Pesce, L. Thijs, J.A. Saito, S. Dewilde, M. Alam, P. Ascenzi, M. Coletta, L. Moens, M. Bolognesi. - In: EMBO REPORTS. - ISSN 1469-221X. - 9:2(2008), pp. 157-163.
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 fromMethanosarcina 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 1.3A°
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 O2, CO and NO to the haem is granted by the protoglobinspecific
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 O2/CO binding to the haem that favours O2 ligation and
anticooperativity in ligand binding. Both properties are
exceptional within the Hb superfamily.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
archaea protein; haemoprotein structure;
methanogenesis; protein matrix tunnels; protoglobin
Elenco autori:
M. Nardini, A. Pesce, L. Thijs, J.A. Saito, S. Dewilde, M. Alam, P. Ascenzi, M. Coletta, L. Moens, M. Bolognesi
Link alla scheda completa: