Glycosaminoglycan (GAG) lyases are often strictly substrate specific, and it is especially difficult to simultaneously degrade GAGs with different types of glycosidic bonds. Herein, we found a new class of GAG lyases (GAGases) from different bacteria. These GAGases belong to polysaccharide lyase 35 family and share quite low homology with the identified GAG lyases. The most surprising thing is that GAGases can not only degrade three types of GAGs: hyaluronan, chondroitin sulfate, and heparan sulfate but also even one of them can also degrade alginate. Further investigation of structural preferences revealed that GAGases selectively act on GAG domains composed of non/6--/-sulfated hexosamines and -glucoronic acids as well as on alginate domains composed of -mannuronic acids. In addition, GAG lyases were once speculated to have evolved from alginate lyases, but no transitional enzymes have been found. The discovery of GAGases not only broadens the category of GAG lyases, provides new enzymatic tools for the structural and functional studies of GAGs with specific structures, but also provides candidates for the evolution of GAG lyases.

中文翻译：

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发现一类具有超宽底物谱的糖胺聚糖裂解酶及其底物结构偏好


糖胺聚糖 (GAG) 裂解酶通常具有严格的底物特异性，同时降解具有不同类型糖苷键的 GAG 尤其困难。在这里，我们发现了来自不同细菌的一类新的 GAG 裂解酶 (GAGases)。这些 GAG 酶属于多糖裂解酶 35 家族，与已鉴定的 GAG 裂解酶同源性相当低。最令人惊讶的是，GAGase不仅可以降解三种类型的GAG：透明质酸、硫酸软骨素和硫酸乙酰肝素，甚至其中一种还可以降解藻酸盐。结构偏好的进一步研究表明，GAGas选择性作用于由非/6-/-硫酸化己糖胺和β-葡萄糖醛酸组成的GAG结构域以及由β-甘露糖醛酸组成的藻酸盐结构域。此外，GAG裂解酶曾被推测是由藻酸盐裂解酶进化而来，但尚未发现过渡酶。 GAGase的发现不仅拓宽了GAG裂解酶的类别，为特定结构的GAG的结构和功能研究提供了新的酶工具，而且为GAG裂解酶的进化提供了候选者。