Ogawa Akinori, Suzumatsu Atsushi, Takizawa Shuichi, Kubota Hiromi, Sawada Kazuhisa, Hakamada Yoshihiro, Kawai Shuji, Kobayashi Tohru, Ito Susumu
Tochigi Research Laboratories of Kao Corporation, 2606 Akabane, Ichikai, Haga, Tochigi 321-3497, Japan.
J Biotechnol. 2007 May 1;129(3):406-14. doi: 10.1016/j.jbiotec.2007.01.020. Epub 2007 Feb 6.
Endoglucanase (Egl)-producing bacteria from soil samples were screened using insoluble cellulosic substrates as sole carbon sources at alkaline pH (pH 9-10). Four Egls with Avicelase activity at alkaline pH were found in the culture broth of each isolate. The Egl genes of the isolates (all Paenibacillus spp.) were shotgun cloned and sequenced-all had a 1752bp open reading frame (584 amino acids) with a putative signal sequence (33 amino acids), and encoded mature enzymes of 551 amino acids (58,360-58,672Da). The mature enzymes showed a high degree of similarity to each other (>93% identity), with the next closest similarity to Egl3a of a patented strain of Paenibacillus lautus NCIMB 40250 (81.5-87.3% identity). These enzymes showed low similarity to other known Egls with less than 50% identity. A representative recombinant enzyme degraded lichenan, carboxymethylcellulose (CMC), glucomannan, acid or alkaline swollen celluloses, and microcrystalline cellulose (Avicel). The optimal pH and temperature of the recombinant enzyme for degrading CMC and Avicel were pH 6.0-8.5 and 45-55 degrees C, respectively. Egls belong to glycoside hydrolase family 5 and form a distinct clan based on the phylogenetic analysis of their amino acid sequences.
以不溶性纤维素底物作为唯一碳源，在碱性pH值（pH 9 - 10）条件下，对从土壤样品中筛选出的产内切葡聚糖酶（Egl）细菌进行了研究。在每个分离株的培养液中发现了4种在碱性pH值下具有纤维二糖酶活性的Egl。对这些分离株（均为芽孢杆菌属）的Egl基因进行了鸟枪法克隆和测序——所有基因都有一个1752bp的开放阅读框（584个氨基酸），带有一个推定的信号序列（33个氨基酸），并编码551个氨基酸（58,360 - 58,672Da）的成熟酶。这些成熟酶彼此之间显示出高度相似性（>93%同一性），与专利菌株劳氏芽孢杆菌NCIMB 40250的Egl3a的次近相似性为81.5 - 87.3%同一性。这些酶与其他已知的Egl显示出低相似性，同一性小于50%。一种代表性的重组酶可降解地衣多糖、羧甲基纤维素（CMC）、葡甘露聚糖、酸性或碱性膨胀纤维素以及微晶纤维素（Avicel）。该重组酶降解CMC和Avicel的最佳pH值和温度分别为pH 6.0 - 8.5和45 - 55摄氏度。Egl属于糖苷水解酶家族5，根据其氨基酸序列的系统发育分析形成一个独特的家族。
