2IBP

Crystal Structure of Citrate Synthase from Pyrobaculum aerophilum

Summary for 2IBP

• Entry DOI: 10.2210/pdb2ibp/pdb
• Descriptor: Citrate synthase, ACETATE ION, MAGNESIUM ION, ... (4 entities in total)
• Functional Keywords: disulfide bond, homodimer, citrate synthase, thermophilic, catenane, transferase
• Biological source: Pyrobaculum aerophilum
• Total number of polymer chains: 2
• Total formula weight: 93049.14

Authors

Boutz, D.R.,Yeates, T.O.,Cascio, D. (deposition date: 2006-09-11, release date: 2007-05-15, Last modification date: 2023-08-30)

Primary citation

Boutz, D.R.,Cascio, D.,Whitelegge, J.,Perry, L.J.,Yeates, T.O.
Discovery of a thermophilic protein complex stabilized by topologically interlinked chains.
J.Mol.Biol., 368:1332-1344, 2007

PubMed Abstract: A growing number of organisms have been discovered inhabiting extreme environments, including temperatures in excess of 100 degrees C. How cellular proteins from such organisms retain their native folds under extreme conditions is still not fully understood. Recent computational and structural studies have identified disulfide bonding as an important mechanism for stabilizing intracellular proteins in certain thermophilic microbes. Here, we present the first proteomic analysis of intracellular disulfide bonding in the hyperthermophilic archaeon Pyrobaculum aerophilum. Our study reveals that the utilization of disulfide bonds extends beyond individual proteins to include many protein-protein complexes. We report the 1.6 A crystal structure of one such complex, a citrate synthase homodimer. The structure contains two intramolecular disulfide bonds, one per subunit, which result in the cyclization of each protein chain in such a way that the two chains are topologically interlinked, rendering them inseparable. This unusual feature emphasizes the variety and sophistication of the molecular mechanisms that can be achieved by evolution.

PubMed: 17395198
DOI: 10.1016/j.jmb.2007.02.078

Experimental method

X-RAY DIFFRACTION (1.6 Å)