tailieunhanh - Báo cáo khoa học: Swollenin, a Trichoderma reesei protein with sequence similarity to the plant expansins, exhibits disruption activity on cellulosic materials

Plant cell wall proteins called expansins are thought to disrupt hydrogen bonding between cell wall polysaccha-rides without hydrolyzing them. We describe here a novel gene with sequence similarity to plant expansins, isolated from the cellulolytic fungus Trichoderma reesei. The pro-tein named swollenin has an N-terminal fungal type cel-lulose binding domain connected by a linker region to the expansin-like domain. | Eur. J. Biochem. 269 4202-4211 2002 FEBS 2002 doi Swollenin a Trichoderma reesei protein with sequence similarity to the plant expansins exhibits disruption activity on cellulosic materials Markku Saloheimo1. Marja Paloheimo1. Satu Hakola1. Jaakko Pere1. Barbara Swanson2 Eini Nvvssonen2 Amit Bhatia2 Michael Ward2 and Merja Penttila1 VTT Biotechnology Finland 2Genencor International Inc. Palo Alto CA USA Plant cell wall proteins called expansins are thought to disrupt hydrogen bonding between cell wall polysaccharides without hydrolyzing them. We describe here a novel gene with sequence similarity to plant expansins isolated from the cellulolytic fungus Trichoderma reesei. The protein named swollenin has an N-terminal fungal type cellulose binding domain connected by a linker region to the expansin-like domain. The protein also contains regions similar to mammalian fibronectin type III repeats found for the first time in a fungal protein. The swollenin gene is regulated in a largely similar manner as the T. reesei cellulase genes. The biological role of SWOI was studied by disrupting the swo1 gene from T. reesei. The disruption had no apparent effect on the growth rate on glucose or on different cellulosic carbon sources. Non-stringent Southern hybridization of Trichoderma genomic DNA with swo1 showed the presence of other swollenin-like genes which could substitute for the loss of SWOI in the disruptant. The swollenin gene was expressed in yeast and Aspergillus niger var. awamori. Activity assays on cotton fibers and filter paper were performed with concentrated SWOI-containing yeast supernatant that disrupted the structure of the cotton fibers without detectable formation of reducing sugars. It also weakened filter paper as assayed by an extensometer. The SWOI protein was purified from A. niger var. awamori culture supernatant and used in an activity assay with Valonia cell walls. It disrupted the structure of the cell walls .