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

Marco Nardini, Alessandra Pesce, Liesbet Thijs, Jennifer A. Saito, Sylvia Dewilde, Maqsudul Alam, Paolo Ascenzi, Massimiliano Coletta, Chiara Ciaccio, Luc Moens, Martino Bolognesi

Research output: Contribution to journalArticle

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.

Original languageEnglish
Pages (from-to)157-163
Number of pages7
JournalEMBO Reports
Volume9
Issue number2
DOIs
Publication statusPublished - Feb 2008

ASJC Scopus subject areas

  • Genetics
  • Cell Biology

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    Nardini, M., Pesce, A., Thijs, L., Saito, J. A., Dewilde, S., Alam, M., Ascenzi, P., Coletta, M., Ciaccio, C., Moens, L., & Bolognesi, M. (2008). Archaeal protoglobin structure indicates new ligand diffusion paths and modulation of haem-reactivity. EMBO Reports, 9(2), 157-163. https://doi.org/10.1038/sj.embor.7401153