tailieunhanh - Báo cáo khoa học: Crystal structure of an ascomycete fungal laccase from Thielavia arenaria – common structural features of asco-laccases

Laccases are copper-containing enzymes used in various applications, such as textile bleaching. Several crystal structures of laccases from fungi and bacteria are available, but ascomycete types of fungal laccases (asco-lac-cases) have been rather unexplored, and to date only the crystal structure ofMelanocarpus albomyceslaccase (MaL) has been published. | IFEBS Journal Crystal structure of an ascomycete fungal laccase from Thielavia arenaria - common structural features of asco-laccases I-VI II-I I- .-2nfl 2 2 2 2 Juha P. Kallio Chiara Gasparetti Martina Andberg Harry Boer Anu Koivula Kristiina Kruus Juha Rouvinen1 and Nina Hakulinen1 1 Department of Chemistry University of Eastern Finland Joensuu Finland 2 VTT TechnicalResearch Centre of Finland Espoo Finland Keywords ascomycete C-terminalplug laccase proton transfer redox potential Correspondence N. Hakulinen Department of Chemistry University of Eastern Finland Joensuu Campus . Box 111 FIN-80101 Joensuu Finland Fax 358 13 2513390 Tel 358 13 2513359 E-mail Received 8 March 2011 revised 20 April 2011 accepted 27 April 2011 doi Laccases are copper-containing enzymes used in various applications such as textile bleaching. Several crystal structures of laccases from fungi and bacteria are available but ascomycete types of fungal laccases asco-lac-cases have been rather unexplored and to date only the crystal structure of Melanocarpus albomyces laccase MaL has been published. We have now solved the crystal structure of another asco-laccase from Thielavi-a arenaria TaLccl at A resolution. The loops near the T1 copper forming the substrate-binding pockets of the two asco-laccases differ to some extent and include the amino acid thought to be responsible for catalytic proton transfer which is Asp in TaLccl and Glu in MaL. In addition the crystal structure of TaLcc1 does not have a chloride attached to the T2 copper as observed in the crystal structure of MaL. The unique feature of TaLcc1 and MaL as compared with other laccases structures is that in both structures the processed C-terminus blocks the T3 solvent channel leading towards the trinuclear centre suggesting a common functional role for this conserved C-terminal plug . We propose that the asco-laccases utilize the C-terminal carboxylic group in proton .