Saxena Hirak, Hsu Bryan, de Asis Marc, Zierke Mirko, Sim Lyann, Withers Stephen G, Wakarchuk Warren
a Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada.
b Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
Biochem Cell Biol. 2018 Feb;96(1):68-76. doi: 10.1139/bcb-2017-0150. Epub 2017 Oct 5.
Bacteria in the genus Cellulomonas are well known as secretors of a variety of mesophilic carbohydrate degrading enzymes (e.g., cellulases and hemicellulases), active against plant cell wall polysaccharides. Recent proteomic analysis of the mesophilic bacterium Cellulomonas fimi ATCC484 revealed uncharacterized enzymes for the hydrolysis of plant cell wall biomass. Celf_1230 (CfCel6C), a secreted protein of Cellulomonas fimi ATCC484, is a novel member of the GH6 family of cellulases that could be successfully expressed in Escherichia coli. This enzyme displayed very little enzymatic/hydrolytic activity at 30 °C, but showed an optimal activity around 65 °C, and exhibited a thermal denaturation temperature of 74 °C. In addition, it also strongly bound to filter paper despite having no recognizable carbohydrate binding module. Our experiments show that CfCel6C is a thermostable endoglucanase with activity on a variety of β-glucans produced by an organism that struggles to grow above 30 °C.
纤维单胞菌属的细菌作为多种中温碳水化合物降解酶（如纤维素酶和半纤维素酶）的分泌者而广为人知，这些酶对植物细胞壁多糖具有活性。最近对中温细菌纤维单胞菌ATCC484的蛋白质组分析揭示了用于水解植物细胞壁生物质的未表征酶。纤维单胞菌ATCC484的分泌蛋白Celf_1230（CfCel6C）是纤维素酶GH6家族的一个新成员，可在大肠杆菌中成功表达。该酶在30℃时酶促/水解活性极低，但在65℃左右表现出最佳活性，热变性温度为74℃。此外，尽管它没有可识别的碳水化合物结合模块，但也能与滤纸强烈结合。我们的实验表明，CfCel6C是一种耐热的内切葡聚糖酶，对一种在30℃以上难以生长的生物体产生的多种β-葡聚糖具有活性。
