Identification and Crystallographic Analysis of a New Carbohydrate Acetylesterase (SmAcE1) from Sinorhizobium meliloti

Carbohydrate-active enzymes (CAZymes) regulate the synthesis, degradation, and modification of the poly-and oligosaccharides in all three kingdoms of life. A novel carbohydrate acetylesterase from Sinorhizobium meliloti, designated SmAcE1, was identified, characterized, and crystallized. This SmAcE1 is classified into the carbohydrate esterase family 3 (CE3) based on the sequence alignments with other currently known carbohydrate esterase (CE) family enzymes. The SmAcE1 was crystallized as a hexamer in a space group P2(1)2(1)2(1) with the unit cell parameters: a = 99.12 angstrom, b = 148.88 angstrom, c = 149.84 angstrom, and alpha = beta = gamma = 90.00 degrees. The diffraction data set was collected up to a 2.05 angstrom resolution. Hydrolysis activity of SmAcE1 towards glucose pentaacetate and cellulose acetate was further confirmed using acetic acid release assay. Further crystallographic and functional analyses studies on SmAcE1 would be followed to fully understand the reaction mechanisms of CEs.