Sequence Analysis and Heterologous Expression of Two Rhamnogalacturonan Acetylesterase Genes (Asrgae1 and Asrgaea2) from a Shoyu Koji Mold, Aspergillus sojae KBN1340

Two rhamnogalacturonan acetylesterase genes, designated as Asrgae1 and Asrgae2, were isolated from a shoyu koji mold, Aspergillus sojae KBN1340, and characterized. Asrgae1 comprised 793 bp, encoding 248 amino acids with a predicted molecular mass of 26,092 Da, interrupted by a single putative intron of 46 bp in length. The mature AsRgae1 of 232 amino acids had a calculated molecular mass of 24,415 Da. The coding region of Asrgae2 was determined to be 777 bp in length with no introns. The predicted protein of 258 amino acids had an estimated molecular mass of 26,902 Da. The mature AsRgae2 of 238 amino acids had a calculated molecular mass of 25,015 Da. Utilizing the A. oryzae taaG2 gene promoter and the A. oryzae taaG3 gene terminator, AsRgae1 and AsRgae2 were successfully expressed in A. oryzae and secreted into the culture medium. AsRgae1 and AsRgae2 had a molecular mass of 28.0 kDa and 33.0 kDa, respectively.