tailieunhanh - Báo cáo khoa học: Antioxidant Dps protein from the thermophilic cyanobacterium Thermosynechococcus elongatus An intrinsically stable cage-like structure endowed with enhanced stability

DNA-binding proteins from starved cells (Dps proteins) protect bacteria primarily from oxidative damage. They are composed of 12 identical subunits assembled with 23-symmetry to form a compact cage-like struc-ture known to be stable at temperatures 70 C and over a wide pH range. Thermosynechococcus elongatus Dps thermostability is increased dramatically relative to mesophilic Dps proteins. | ỊFEBS Journal Antioxidant Dps protein from the thermophilic cyanobacterium Thermosynechococcus elongatus An intrinsically stable cage-like structure endowed with enhanced stability Stefano Franceschini Pierpaolo Ceci Flaminia Alaleona Emilia Chiancone and Andrea Ilari . Institute of Molecular Biology and Pathology University of Rome La Sapienza Italy Keywords Dps from Thermosynechococcus elongatus hydrogen peroxide iron oxidation thermostability X-ray structure Correspondence A. Ilari Istituto di Biologia e Patologia Molecolari CNR Dipartimento di Scienze Biochimiche Universita di Roma La Sapienza A. Moro 5 00185 Rome Italy Fax 39 06 444 0062 Tel. 39 06 494 0543 499 10761 E-mail Database The atomic coordinates and structure factors have been deposited in the Protein Data Bank Research Laboratory for Struc-turalBioinformatics Rutgers University New Brunswick http PDB code 2C41 DNA-binding proteins from starved cells Dps proteins protect bacteria primarily from oxidative damage. They are composed of 12 identical subunits assembled with 23-symmetry to form a compact cage-like structure known to be stable at temperatures 70 C and over a wide pH range. Thermosynechococcus elongatus Dps thermostability is increased dramatically relative to mesophilic Dps proteins. Hydrophobic interactions at the dimeric and trimeric interfaces called Dps-like are replaced by salt bridges and hydrogen bonds a common strategy in thermophiles. Moreover the buried surface area at the least-extended Dps-like interface is significantly increased. A peculiarity of T. elongatus Dps is the presence of a chloride ion coordinated with threefold symmetry-related arginine residues lining the opening of the Dps-like pore toward the internal cavity. T. elongatus Dps conserves the unusual intersubunit ferr-oxidase centre that allows the Dps protein family to oxidize Fe II with hydrogen peroxide thereby inhibiting free radical production via Fenton .