|
 |
|
|
|
EMBO reports 9, 2, 157–163 (2008)
doi:10.1038/sj.embor.7401153
AOP Published online: 11 January 2008
Archaeal protoglobin structure indicates new ligand diffusion paths and modulation of haem-reactivity
Marco Nardini1, Alessandra Pesce2, Liesbet Thijs3, Jennifer A Saito4, Sylvia Dewilde3, Maqsudul Alam4, Paolo Ascenzi5, Massimiliano Coletta6, Chiara Ciaccio6, Luc Moens3 & Martino Bolognesi1
|
|
|
|
1 Department of Biomolecular Sciences and Biotechnology, CNR-INFM, University of Milano, Via Celoria 26, Milano 20133, Italy
2 Department of Physics, CNR-INFM and CEBR, University of Genova, Via Dodecaneso, 33, Genova 16146, Italy
3 Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, Antwerp B-2610, Belgium
4 Department of Microbiology, University of Hawaii, Snyder Hall 207, 2538 The Mall, Honolulu, Hawaii 96822, USA
5 Department of Biology and Interdepartmental Laboratory for Electron Microscopy, University Roma Tre, Viale Guglielmo Marconi 446, Roma 00146, Italy
6 Department of Experimental Medicine and Biochemical Sciences, University of Roma 'Tor Vergata', Via di Tor Vergata 135, Roma 00133, Italy
To whom correspondence should be addressed
Martino Bolognesi Tel: +39 02 50314893; Fax: +39 02 50314895; E-mail: martino.bolognesi@unimi.it
Received 30 July 2007; Accepted 19 November 2007; Published online 11 January 2008.
|
|
|
|
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 1.3 Å 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 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 O2/CO binding to the haem that favours O2 ligation and anticooperativity in ligand binding. Both properties are exceptional within the Hb superfamily.
|
 |
|
Top of page MORE ARTICLES LIKE THIS These links to content published by NPG are automatically generated | |
|
top  |
|
|
|
