Study of new feruloyl esterases to understand lipase evolution: the case of Bacillus flexus

Recently, the crystal structure of the feruloyl esterase A from Aspergillus niger (AnFaeA) was elucidated. This enzyme displays an α/β hydrolase fold and a catalytic triad similar to that found in fungal lipases (30-37% identity). Surprisingly, AnFaeA showed an overall fold similarity with the Rhizomucor miehei and other related fungal lipases. All these data strongly suggest that the ancestral function (lipase) had shifted, with molecular adaptation leading to a novel enzyme (type-A feruloyl esterase). The discovery of new feruloyl esterases could lead to get insight into the evolutionary pathways of these enzymes and into new possibilities of directed evolution of lipases. In this chapter, the production of Bacillus flexus NJY2 feruloyl esterases is described. Unlike the previously described feruloyl esterases, which mostly belong to eukaryotes (mainly fungus), this unique feruloyl esterases from a prokaryotic alkaliphile microorganism could be the starting point for new discoveries on lipase and feruloyl esterase evolutionary relationships.