Unité des Aspergillus, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France.
J Biol Chem. 2010 Jan 22;285(4):2386-96. doi: 10.1074/jbc.M109.077545. Epub 2009 Nov 30.
A new HPLC method was developed to separate linear from beta(1-6)-branched beta(1-3)-glucooligosaccharides. This methodology has permitted the isolation of the first fungal beta(1-6)/beta(1-3)-glucan branching transglycosidase using a cell wall autolysate of Aspergillus fumigatus (Af). The encoding gene, AfBGT2 is an ortholog of AfBGT1, another transglycosidase of A. fumigatus previously analyzed (Mouyna, I., Hartland, R. P., Fontaine, T., Diaquin, M., Simenel, C., Delepierre, M., Henrissat, B., and Latgé, J. P. (1998) Microbiology 144, 3171-3180). Both enzymes release laminaribiose from the reducing end of a beta(1-3)-linked oligosaccharide and transfer the remaining chain to another molecule of the original substrate. The AfBgt1p transfer occurs at C-6 of the non-reducing end group of the acceptor, creating a kinked beta(1-3;1-6) linear molecule. The AfBgt2p transfer takes place at the C-6 of an internal group of the acceptor, resulting in a beta(1-3)-linked product with a beta(1-6)-linked side branch. The single Afbgt2 mutant and the double Afbgt1/Afbgt2 mutant in A. fumigatus did not display any cell wall phenotype showing that these activities were not responsible for the construction of the branched beta(1-3)-glucans of the cell wall.
建立了一种新的 HPLC 方法以分离直链和β(1-6)-支链β(1-3)-葡寡糖。该方法允许使用烟曲霉(Asp. fumigatus)的细胞壁自溶产物分离到第一个真菌β(1-6)/β(1-3)-葡聚糖分支转糖苷酶。编码基因 AfBGT2 是 AfBGT1 的同源物,AfBGT1 是先前分析的烟曲霉的另一种转糖苷酶(Mouyna,I.,Hartland,R. P.,Fontaine,T.,Diaquin,M.,Simenel,C.,Delepierre,M.,Henrissat,B.和 Latgé,J. P.(1998)Microbiology 144,3171-3180)。两种酶都从β(1-3)-连接的寡糖的还原端释放出纤维二糖,并将剩余的链转移到原始底物的另一个分子上。AfBgt1p 转移发生在受体非还原端基团的 C-6 上,形成一个扭曲的β(1-3;1-6)直链分子。AfBgt2p 转移发生在受体内部基团的 C-6 上,导致具有β(1-6)-连接侧支的β(1-3)-连接产物。在烟曲霉中,单个 Afbgt2 突变体和 Afbgt1/Afbgt2 双突变体均未显示任何细胞壁表型,表明这些活性不是细胞壁分支β(1-3)-葡聚糖构建的原因。