1Z9P

X-Ray structure of a Cu-Zn superoxide dismutase from Haemophilus ducreyi

Summary for 1Z9P

• Entry DOI: 10.2210/pdb1z9p/pdb
• Related: 1BZO 1YAI 2APS
• Descriptor: Superoxide dismutase [Cu-Zn], COPPER (II) ION, ZINC ION, ... (4 entities in total)
• Functional Keywords: cu-zn sod, sod, metalloenzymes, oxidoreductase
• Biological source: Haemophilus ducreyi
• Cellular location: Periplasm: Q59452
• Total number of polymer chains: 2
• Total formula weight: 33287.44

Authors

Djinovic Carugo, K.,Toeroe, I. (deposition date: 2005-04-04, release date: 2006-09-12, Last modification date: 2024-10-30)

Primary citation

Toro, I.,Petrutz, C.,Pacello, F.,D'Orazio, M.,Battistoni, A.,Djinovic-Carugo, K.
Structural basis of heme binding in the Cu,Zn superoxide dismutase from Haemophilus ducreyi.
J.Mol.Biol., 386:406-418, 2009

PubMed Abstract: The Cu,Zn superoxide dismutase from Haemophilus ducreyi is characterized by the unique ability to bind heme at its dimer interface. Here we report the high-resolution crystal structures of this protein in the heme-loaded (holo) and heme-free (apo) forms. Heme is asymmetrically bound between the two enzyme subunits, where heme iron is coordinated by two histidine residues, His64 and His 124, provided by the two subunits. Moreover, the binding of heme to the protein is ensured by stabilizing contacts between the prosthetic group and a limited number of other residues, most of which are not present in other bacterial enzyme variants. We show that the introduction of only three mutations at the dimer interface of the enzyme from Haemophilus parainfluenzae, a closely related bacterial species, is sufficient to induce heme-binding ability by this enzyme variant. Heme binding does not alter protein activity. Moreover, the binding of the prosthetic group does not induce any significant structural perturbation at the subunit level and requires only limited local structural rearrangements that widen the cleft at the dimer interface and cause a limited shift in the relative orientation between the subunits. The presence of a preformed heme-binding pocket and the significant solvent exposure of the cofactor to the solvent are compatible with the suggested protective role of the enzyme against heme toxicity or with its involvement in heme trafficking in the periplasmic space.

PubMed: 19103206
DOI: 10.1016/j.jmb.2008.12.004

Experimental method

X-RAY DIFFRACTION (1.5 Å)