Cloning and expression of the pectin methyl esterase gene from DCE-01 strain

Primers were designed by the potential pectin methyl esterase gene annotated from the whole genome sequence of DCE- 01 strain, which is an efficient strain for bast fiber bio- extracting. The pectin methyl esterase gene was cloned, linked to pEASY- E1, and expressed in Escherichia coli BL21 ( DE3) .The positive colonies were selected by the hydrolysis circles, and then their pectin methyl esterase activities were analyzed. It was resulted that the pectin methyl esterase gene ( GenBank: KC422449 ) was 1107bp and encoded 368 amino acids. By the bioinformatics software analysis, the 26 amino acids in front of the protein sequence were signal peptide. The molecular weight of pre-PME was approximately 39.6ku, the molecular weight of mature- PME was 36.9ku, and pI was 9.1.With high methoxyl citrus pectin as substrate, the pectin methyl esterase activity secreted by the genetic engineering strain was 1.5IU /mL, 22.4 times higher than that from the original DCE- 01 strain. An efficient pectin methyl esterase gene had been excavated from the DCE-01 strain, and its expression product could degrade high methoxyl pectin, so it might be available for low methoxyl pectin preparation.