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

Structure. 2002 May;10(5):725-35. doi: 10.1016/s0969-2126(02)00763-3.

Abstract

A very short hemoglobin (CerHb; 109 amino acids) binds O(2) 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 A 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 O(2) 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Hemoglobins / chemistry*
  • Hemoglobins / genetics
  • Hemoglobins / metabolism
  • Humans
  • Invertebrates / chemistry*
  • Models, Molecular
  • Molecular Sequence Data
  • Molecular Structure
  • Nerve Tissue Proteins / chemistry*
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism
  • Protein Folding
  • Protein Structure, Tertiary*
  • Sequence Alignment

Substances

  • Hemoglobins
  • Nerve Tissue Proteins

Associated data

  • PDB/1KR7