A feruloyl esterase derived from a leachate metagenome library

Abstract

A feruloyl esterase encoding gene (designated fae6), derived from a leachate metagenomic library, was cloned and the nucleotide sequence of the insert DNA determined. Translational analysis revealed that fae6 consists of a 515 amino acid polypeptide, encoding a 55 kDa pre-protein. The Fae6 primary structure contained the G-E-S-A-G sequence, which corresponds well with a typical catalytic serine sequence motif (G-x-S-x-G). The fae6 gene was successfully over-expressed in E. coli and the recombinant protein was purified to 8.4 fold enrichment with 17% recovery. The KM data showed Fae6 has a high affinity to methyl sinapate while thermostability data indicated that Fae6 was thermolabile with a half life (T1/2) < 30 min at 50oC. High affinity for Fae6 against methyl sinapate, methyl ferulate and ethyl ferulate suggest that the enzyme can be useful in hydrolyzing ferulated polysaccharides in a biorefinery process.