Identification and functional analysis thoef gfsA gene involved in the biosynthesis of galactofuranose containing oligosaccharides

丝状真菌的壁含有含呋喃半乳糖的多糖和糖缀合物。呋喃半乳糖残基被认为对曲霉细胞壁的完整性是重要的，然而，参与呋喃半乳糖抗原生物合成的呋喃半乳糖基转移酶先前尚未被鉴定。我们使用反向遗传学和生物化学方法鉴定了A。nidulans的gfsA基因负责半乳糖呋喃糖抗原的生物合成。gfsA的破坏降低了与EB-A2抗体的反应性，EB-A2抗体识别b-呋喃半乳糖残基、半乳甘露糖蛋白和纯化的WscA，WscA是细胞表面的O-糖基化传感器蛋白之一。体外呋喃半乳糖抗原合成酶测定的结果显示，纯化的GfsA具有呋喃半乳糖基转移酶活性，需要二价锰阳离子，并消耗UDP-D-呋喃半乳糖作为糖供体。这是首次鉴定真菌-呋喃半乳糖基转移酶

The walls of filamentous fungi contain galactofuranose-containing polysaccharides and glycoconjugates. Galactofuranose residues are thought be important for Aspergillus cell wall integrity, however, galactofuranosyltransferases involved in galactofuranose antigens biosynthesis have not previously been identified. We used reverse-genetic and biochemical approaches to identify A. nidulans the gfsA gene which is responsible for galactofuranose antigen biosynthesis. Disruption of gfsA reduces reactivity with the EB-A2 antibody, which recognizes b-galactofuranose residue, to galactomannoproteins and to the purified WscA, which is one of O-glycosylated sensor protein of cell surface. The results of an in vitro galactofuranose antigen synthase assay revealed that the purified GfsA has a galactofuranosyltransferase activity and requires a divalent manganese cation and consumes UDP-D-galactofuranose as a sugar donor. This is the first characterization of fungalb-galactofuranosyltransferae