2ig3

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spinqualitylabelsall models 2ig3, resolution 2.15Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of group III truncated hemoglobin from Campylobacter jejuni

Overview

Truncated hemoglobins (trHbs) constitute a distinct lineage in the globin, superfamily, distantly related in size and fold to myoglobin and monomeric, hemoglobins. Their phylogenetic analyses revealed that three groups (I, II, and III) compose the trHb family. Group I and II trHbs adopt a, simplified globin fold, essentially composed of a 2-on-2 alpha-helical, sandwich, wrapped around the heme group. So far no structural data have, been reported for group III trHbs. Here we report the three-dimensional, structure of the group III trHbP from the eubacterium Campylobacter, jejuni. The 2.15-A resolution crystal structure of C. jejuni trHbP, (cyano-met form) shows that the 2-on-2 trHb fold is substantially, conserved in the trHb group III, despite the absence of the Gly-based, sequence motifs that were considered necessary for the attainment of the, trHb specific fold. The heme crevice presents important structural, modifications in the C-E region and in the FG helical hinge, with novel, surface clefts at the proximal heme site. Contrary to what has been, observed for group I and II trHbs, no protein matrix tunnel/cavity system, is evident in C. jejuni trHbP. A gating movement of His(E7) side chain, (found in two alternate conformations in the crystal structure) may be, instrumental for ligand entry to the heme distal site. Sequence, conservation allows extrapolating part of the structural results here, reported to the whole trHb group III.

About this Structure

2IG3 is a Single protein structure of sequence from Campylobacter jejuni with CYN, ACT, SO4 and HEM as ligands. Full crystallographic information is available from OCA.

Reference

Structural determinants in the group III truncated hemoglobin from Campylobacter jejuni., Nardini M, Pesce A, Labarre M, Richard C, Bolli A, Ascenzi P, Guertin M, Bolognesi M, J Biol Chem. 2006 Dec 8;281(49):37803-12. Epub 2006 Oct 5. PMID:17023416

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