Department of Food Science and Biotechnology, Kyungsung University, Busan, 608-736, Korea.
Appl Microbiol Biotechnol. 2014 Mar;98(5):2145-54. doi: 10.1007/s00253-013-5126-0. Epub 2013 Jul 30.
A novel acetylalginate esterase (AcAlgE) gene was cloned and characterized from the genomic DNA library of Sphingomonas sp. MJ-3. A putative gene encoding AcAlgE protein of 292-residue precursor protein with 20-amino acid signal peptide was identified in the alg operon. The deduced AcAlgE protein has GDSL-like consensus motif and shares a highest sequence identity (51%) with GDSL family lipolytic protein from Pseudoxanthomonas suwonensis. Enzymatic assays with bacterial acetylalginate as the substrate showed that the recombinant AcAlgE protein possesses deacetylation activity. The optimal temperature and pH for the AcAlgE were 22 °C and pH 6.5 (citrate buffer), respectively. The recombinant AcAlgE protein catalyzed deacetylation of acetylalginate with release of acetate. The resulting de-acetylated alginate was readily degraded by alginate lyases, indicating that the recombinant AcAlgE enhanced the subsequent degradation of acetylalginate by alginate lyases. The recombinant AcAlgE can play an important role in the degradation of acetylated alginate such as mucoidal acetylalginate in cystic fibrosis patient.
从鞘氨醇单胞菌 MJ-3 的基因组 DNA 文库中克隆并鉴定了一种新型乙酰海藻酸盐酯酶 (AcAlgE) 基因。在 alg 操纵子中鉴定到一个推定的编码 AcAlgE 蛋白的基因，该蛋白由 292 个残基的前体蛋白组成，带有 20 个氨基酸的信号肽。推导的 AcAlgE 蛋白具有 GDSL 样保守基序，与 Pseudoxanthomonas suwonensis 的 GDSL 家族脂肪酶的序列同一性最高（51%）。用细菌乙酰海藻酸盐作为底物进行的酶促测定表明，重组 AcAlgE 蛋白具有脱乙酰基活性。AcAlgE 的最适温度和 pH 分别为 22°C 和 pH 6.5（柠檬酸盐缓冲液）。重组 AcAlgE 蛋白催化乙酰海藻酸盐的脱乙酰化，释放出乙酸盐。所得脱乙酰化的海藻酸盐容易被海藻酸盐裂解酶降解，表明重组 AcAlgE 增强了海藻酸盐裂解酶对乙酰化海藻酸盐的后续降解。重组 AcAlgE 可以在囊性纤维化患者的粘蛋白乙酰海藻酸盐等乙酰化海藻酸盐的降解中发挥重要作用。
