Cellouronate is a (1,4)-β-D-glucuronan prepared by TEMPO-mediated oxidation from regenerated cellulose. We have previously isolated a cellouronate-degrading bacterial strain, Brevundimonas sp. SH203, that produces a cellouronate lyase (β-1,4-glucuronan lyase, CUL-I). In this study, the gene encoding CUL-I was cloned, and the recombinant enzyme was heterologously expressed in Escherichia coli. The predicted CUL-I protein is composed of 426 amino acid residues and includes a putative 21-amino acid signal peptide. The recombinant CUL-I specifically depolymerized β-1,4-glycoside linkages of cellouronate, and its mode of action was endo-type, like the native CUL-I. Sequence analysis showed CUL-I has no similarity to previously known polysaccharide lyases (PLs), indicating that CUL-I should be classified into a novel PL family.

中文翻译：

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来自Brevundimonas sp。的细菌内切β-1，4-葡糖醛酸聚糖裂解酶CUL-1。SH203，属于新的多糖裂解酶家族。

纤维绒酸酯是通过TEMPO介导的再生纤维素氧化制备的（1,4）-β-D-葡糖醛酸聚糖。我们以前曾分离出可降解纤维素的细菌，即Brevundimonas sp.。SH203，其产生纤维素酸裂合酶（β-1，4-葡糖醛酸聚糖裂合酶，CUL-1）。在该研究中，克隆了编码CUL-1的基因，并且重组酶在大肠杆菌中异源表达。预测的CUL-1蛋白由426个氨基酸残基组成，并包括一个推定的21个氨基酸信号肽。重组CUL-1特异解聚了纤维绒素的β-1,4-糖苷键，其作用方式像天然CUL-1一样是内切型的。序列分析显示CUL-1与先前已知的多糖裂解酶（PL）没有相似性，表明CUL-1应分类为新的PL家族。