PDBsum entry 1it3

Oxygen storage/transport

PDB id: 1it3

Contents

Protein chains

146 a.a. *

Ligands

HEM-CMO ×4

Waters ×270

* Residue conservation analysis

PDB id:

1it3

Name:

Oxygen storage/transport

Title:

Hagfish co ligand hemoglobin

Structure:

Hemoglobin. Chain: a, b, c, d

Source:

Eptatretus burgeri. Inshore hagfish. Organism_taxid: 7764

Resolution:

2.10Å R-factor: 0.196 R-free: 0.285

Authors:

M.Mito,K.T.Chong,S.-Y.Park,J.R.Tame

Key ref:

M.Mito et al. (2002). Crystal structures of deoxy- and carbonmonoxyhemoglobin F1 from the hagfish Eptatretus burgeri. J Biol Chem, 277, 21898-21905. PubMed id: 11923284 DOI: 10.1074/jbc.M111492200

Date:

05-Jan-02 Release date: 23-Jan-02

Protein chains

Q7SID0  (GLBF1_EPTBU) -  Globin-F1 from Eptatretus burgeri

Seq: 146 a.a.

Struc: 146 a.a.

DOI no: 10.1074/jbc.M111492200

J Biol Chem 277:21898-21905 (2002)

PubMed id: 11923284

Crystal structures of deoxy- and carbonmonoxyhemoglobin F1 from the hagfish Eptatretus burgeri.

M.Mito, K.T.Chong, G.Miyazaki, S.Adachi, S.Y.Park, J.R.Tame, H.Morimoto.

ABSTRACT

Hagfish are extremely primitive jawless fish of disputed ancestry. Although generally classed with lampreys as cyclostomes ("round mouths"), it is clear that they diverged from them several hundred million years ago. The crystal structures of the deoxy and CO forms of hemoglobin from a hagfish (Eptatretus burgeri) have been solved at 1.6 and 2.1 A, respectively. The deoxy crystal contains one dimer and two monomers in a unit cell, with the dimer being similar to that found in lamprey deoxy-Hb, but with a larger interface and different relative orientation of the partner chains. Ile(E11) and Gln(E7) obstruct ligand binding in the deoxy form and make room for ligands in the CO form, but no interaction path between the two hemes could be identified. The BGH core structure, which forms the alpha1beta1 interface of all vertebrate alpha2beta2 tetrameric Hbs, is conserved in hagfish and lamprey Hbs. It was shown previously that human and cartilaginous fish Hbs have independently evolved stereochemical mechanisms other than the movement of the proximal histidine to regulate ligand binding at the hemes. Our results therefore suggest that the formation of the alpha2beta2 tetramer using the BGH core and the mechanism of quaternary structure change evolved between the branching points of hagfish and lampreys from other vertebrates.

Selected figure(s)

Figure 3.
Fig. 3. Comparison of the E. burgeri deoxy-Hb F1 dimer (A) with the lamprey Hb V dimer (B) (Protein Data Bank code 3lhb). The E and F helices and AB corners are indicated. Lamprey deoxy-Hb has a more open conformation in the upper half of the interface, and the F helices do not contribute to dimer formation.

Figure 6.
Fig. 6. 2F[o] F[c] electron density map showing the heme of deoxy-Hb F1. The map is contoured at 1.3 and clearly shows the absence of ligand bound to the heme. The resolution of the data is high enough to model the side chain conformations of residues around the heme unambiguously.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2002, 277, 21898-21905) copyright 2002.

Figures were selected by an automated process.