tailieunhanh - Báo cáo khoa học: Crystal structure of heme oxygenase-1 from cyanobacterium Synechocystis sp. PCC 6803 in complex with heme

Heme oxygenase (HO) catalyzes the oxidative degradation of heme utilizing molecular oxygen and reducing equiva-lents. In photosynthetic organisms, HO functions in the biosynthesis of such open-chain tetrapyrroles as phyto-chromobilin and phycobilins, which are involved in the sig-nal transduction for light responses and light harvesting for photosynthesis, respectively. | Eur. J. Biochem. 271 4517-4525 2004 FEBS 2004 doi Crystal structure of heme oxygenase-1 from cyanobacterium Synechocystis sp. PCC 6803 in complex with heme Masakazu Sugishima1 Catharina T. Migita2 Xuhong Zhang3 Tadashi Yoshida3 and Keiichi Fukuyama1 1Department of Biology Graduate School of Science Osaka University Toyonaka Osaka Japan department of Biological Chemistry Faculty of Agriculture Yamaguchi University Yoshida Yamaguchi Japan 3Department of Biochemistry Yamagata University School of Medicine Yamagata Japan Heme oxygenase HO catalyzes the oxidative degradation of heme utilizing molecular oxygen and reducing equivalents. In photosynthetic organisms HO functions in the biosynthesis of such open-chain tetrapyrroles as phyto-chromobilin and phycobilins which are involved in the signal transduction for light responses and light harvesting for photosynthesis respectively. We have determined the first crystal structure of a HO-1 from a photosynthetic organism Synechocystis sp. PCC 6803 Syn HO-1 in complex with heme at A resolution. Heme-Syn HO-1 shares a common folding with other heme-HOs. Although the heme pocket of heme-Syn HO-1 is for the most part similar to that of mammalian HO-1 they differ in such features as the flexibility of the distal helix and hydrophobicity. In addition 2-propanol derived from the crystallization solution occupied the hydrophobic cavity which is proposed to be a CO trapping site in rat HO-1 that suppresses product inhibition. Although Syn HO-1 and mammalian HO-1 are similar in overall structure and amino acid sequence 57 similarity vs. human HO-1 their molecular surfaces differ in charge distribution. The surfaces of the heme binding sides are both positively charged but this patch of Syn HO-1 is narrow compared to that of mammalian HO-1. This feature is suited to the selective binding of ferredoxin the physiological redox partner of Syn HO-1 the molecular size of ferredoxin is w 10 kDa whereas .