2VXX

X-ray structure of DpsA from Thermosynechococcus elongatus

Summary for 2VXX

• Entry DOI: 10.2210/pdb2vxx/pdb
• Descriptor: STARVATION INDUCED DNA BINDING PROTEIN, ZINC ION, FE (III) ION, ... (6 entities in total)
• Functional Keywords: stress response protein, dna-binding protein, dps, oxidation, iron binding, ferroxidase centre, dna binding protein
• Biological source: SYNECHOCOCCUS ELONGATUS
• Total number of polymer chains: 4
• Total formula weight: 87657.51

Authors

Franceschini, S.,Ilari, A. (deposition date: 2008-07-14, release date: 2009-11-17, Last modification date: 2023-12-13)

Primary citation

Alaleona, F.,Franceschini, S.,Ceci, P.,Ilari, A.,Chiancone, E.
Thermosynechococcus Elongatus Dpsa Binds Zn(II) at a Unique Three Histidine-Containing Ferroxidase Center and Utilizes O2 as Iron Oxidant with Very High Efficiency, Unlike the Typical Dps Proteins.
FEBS J., 277:903-, 2010

PubMed Abstract: The cyanobacterium Thermosynechococcus elongatus is one the few bacteria to possess two Dps proteins, DpsA-Te and Dps-Te. The present characterization of DpsA-Te reveals unusual structural and functional features that differentiate it from Dps-Te and the other known Dps proteins. Notably, two Zn(II) are bound at the ferroxidase center, owing to the unique substitution of a metal ligand at the A-site (His78 in place of the canonical aspartate) and to the presence of a histidine (His164) in place of a hydrophobic residue at a metal-coordinating distance in the B-site. Only the latter Zn(II) is displaced by incoming iron, such that Zn(II)-Fe(III) complexes are formed upon oxidation, as indicated by absorbance and atomic emission spectroscopy data. In contrast to the typical behavior of Dps proteins, where Fe(II) oxidation by H(2)O(2) is about 100-fold faster than by O(2), in DpsA-Te the ferroxidation efficiency of O(2) is very high and resembles that of H(2)O(2). Oxygraphic experiments show that two Fe(II) are required to reduce O(2), and that H(2)O(2) is not released into solution at the end of the reaction. On this basis, a reaction mechanism is proposed that also takes into account the formation of Zn(II)-Fe(III) complexes. The physiological significance of the DpsA-Te behavior is discussed in the framework of a possible localization of the protein at the thylakoid membranes, where photosynthesis takes place, with the consequent increased formation of reactive oxygen species.

PubMed: 20088882
DOI: 10.1111/J.1742-4658.2009.07532.X

Experimental method

X-RAY DIFFRACTION (2.4 Å)