Structural highlights
Publication Abstract from PubMedLaccases 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 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 Thielavia arenaria (TaLcc1) at 2.5 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 TaLcc1 instead of Glu observed 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 the TaLcc1 and MaL compared to 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 ascomycete laccases utilize the C-terminal carboxylic group in proton transfer processes, similarly as has been suggested for the Glu498 in the CotA-laccase from Bacillus subtilis (BsL). The crystal structure of TaLcc1 also shows the formation of a similar weak homodimer as observed for MaL that may determine the properties of these asco-laccases at high protein concentrations. Crystal structure of an ascomycete fungal laccase from Thielavia arenaria: Common structural features of asco-laccases.,Kallio JP, Gasparetti C, Andberg M, Boer H, Koivula A, Kruus K, Rouvinen J, Hakulinen N FEBS J. 2011 Apr 29. doi: 10.1111/j.1742-4658.2011.08146.x. PMID:21535408[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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