A very short hemoglobin (CerHb; 109 amino acids) binds O2 cooperatively in the nerve tissue of the nemertean worm Cerebratulus lacteus to sustain neural activity during anoxia. Sequence analysis suggests that CerHb tertiary structure may be unique among the known globin fold evolutionary variants. The X-ray structure of oxygenated CerHb (R factor 15.3%, at 1.5 Å resolution) displays deletion of the globin N-terminal A helix, an extended GH region, a very short H helix, and heme solvent shielding based on specific aromatic residues. The heme-bound O2 is stabilized by hydrogen bonds to the distal TyrB10-GlnE7 pair. Ligand access to heme may take place through a wide protein matrix tunnel connecting the distal site to a surface cleft located between the E and H helices.

The 109 residue nerve tissue minihemoglobin from Cerebratulus lacteus highlights striking structural plasticity of the α-helical globin fold / A. Pesce, M. Nardini, S. Dewilde, E. Geuens, K. Yamauchi, P. Ascenzi, A.F. Riggs, L. Moens, M. Bolognesi. - In: STRUCTURE. - ISSN 0969-2126. - 10:5(2002 May), pp. 725-735.

The 109 residue nerve tissue minihemoglobin from Cerebratulus lacteus highlights striking structural plasticity of the α-helical globin fold

Nardini, Marco;Bolognesi, Martino
2002-05

Abstract

A very short hemoglobin (CerHb; 109 amino acids) binds O2 cooperatively in the nerve tissue of the nemertean worm Cerebratulus lacteus to sustain neural activity during anoxia. Sequence analysis suggests that CerHb tertiary structure may be unique among the known globin fold evolutionary variants. The X-ray structure of oxygenated CerHb (R factor 15.3%, at 1.5 Å resolution) displays deletion of the globin N-terminal A helix, an extended GH region, a very short H helix, and heme solvent shielding based on specific aromatic residues. The heme-bound O2 is stabilized by hydrogen bonds to the distal TyrB10-GlnE7 pair. Ligand access to heme may take place through a wide protein matrix tunnel connecting the distal site to a surface cleft located between the E and H helices.
globin fold plasticity; nerve tissue minihemoglobin; oxygen binding; oxygenated hemoglobin; protein cavities; X-ray crystallography
Settore BIO/10 - Biochimica
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/638776
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