Hydrolysis of β-1,3/1,6-glucan by glycoside hydrolase family 16 endo-1,3(4)-β-glucanase from the basidiomycete Phanerochaete chrysosporium
Hydrolysis of β-1,3/1,6-glucan by glycoside hydrolase family 16 endo-1,3(4)-β-glucanase from the basidiomycete Phanerochaete chrysosporium
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DOI：
10.1007/s00253-005-0214-4
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发表时间：
2006-08-01
影响因子：
5
通讯作者：
Samejima, Masahiro
中科院分区：
文献类型：
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作者：
Kawai, Rie;Igarashi, Kiyohiko;Samejima, Masahiro
当金孢原毛平革菌以昆布多糖（一种 β-1,3/1,6-葡聚糖）作为唯一碳源生长时，会产生一种分子量为 36 kDa 的 β-1,3-葡聚糖酶作为主要的细胞外蛋白。克隆了编码该酶的cDNA，推导的氨基酸序列显示该酶属于糖苷水解酶家族16；它被命名为 Lam16A。重组 Lam16A 在甲基营养酵母毕赤酵母中表达，随机水解线性 β-1,3-葡聚糖、支链 β-1,3/1,6-葡聚糖和 β-1,3-1,4-葡聚糖，表明该酶是一种典型的内切 1,3(4)-β-葡聚糖酶 (EC 3.2.1.6)，具有广泛的用途。 (3-1,β-葡聚糖) 的底物特异性。当使用昆布多糖和地衣多糖作为底物时，Lam16A 产生 6-O-葡萄糖基-昆布三糖 (beta-D-Glcp-(1-> 6)-(beta-D-Glcp-(1-> 3)-(3-D-Glcp-(1-> 3)-D-Glc) 和 4-O-葡萄糖基昆布二糖（β-D-Glcp-(1-> 4)-(3-D-Glcp(1-> 3)-D-Glc)分别是主要产物之一。这些结果表明该酶严格识别子位点-2和-1处的(3-D-Glcp-(1-> 3)-D-Glcp，而它允许6-O-葡萄糖基 +1 子位点的取代和催化位点的 β-1,4-糖苷键。因此，Lam16A 从支链 β-1,3/1,6-葡聚糖生成非支链寡糖，因此与其他胞外 β-1,3-葡聚糖酶结合可能有助于此类分子的有效降解。
When Phanerochaete chrysosporium was grown with laminarin (a beta-1,3/1,6-glucan) as the sole carbon source, a beta-1,3-glucanase with a molecular mass of 36 kDa was produced as a major extracellular protein. The cDNA encoding this enzyme was cloned, and the deduced amino acid sequence revealed that this enzyme belongs to glycoside hydrolase family 16; it was named Lam16A. Recombinant Lam16A, expressed in the methylotrophic yeast Pichia pastoris, randomly hydrolyzes linear beta-1,3-glucan, branched beta-1,3/1,6-glucan, and beta-1,3-1,4-glucan, suggesting that the enzyme is a typical endo-1,3(4)-beta-glucanase (EC 3.2.1.6) with broad substrate specificity for (3-1,beta-glucans. When laminarin and lichenan were used as substrates, Lam16A produced 6-O-glucosyl-laminaritriose (beta-D-Glcp-(1-> 6)-(beta-D-Glcp-(1-> 3)-(3-D-Glcp-(1-> 3)-D-Glc) and 4-O-glucosyl-laminaribiose (beta-D-Glcp-(1-> 4)-(3-D-Glcp(1-> 3)-D-Glc), respectively, as one of the major products. These results suggested that the enzyme strictly recognizes (3-D-Glcp-(1-> 3)-D-Glcp at subsites -2 and -1, whereas it permits 6-O-glucosyl substitution at subsite +1 and a beta-1,4-glucosidic linkage at the catalytic site. Consequently, Lam16A generates non-branched oligosaccharide from branched beta-1,3/1,6-glucan and, thus, may contribute to the effective degradation of such molecules in combination with other extracellular beta-1,3-glucanases.