Saturated mutagenesis of ketoisovalerate decarboxylase V461 enabled specific synthesis of 1-pentanol via the ketoacid elongation cycle.

Iterative ketoacid elongation has been an essential tool in engineering artificial metabolism, in particular the synthetic alcohols. However, precise control of product specificity is still greatly challenged by the substrate promiscuity of the ketoacid decarboxylase, which unselectively hijacks ketoacid intermediates from the elongation cycle along with the target ketoacid. In this work, preferential tuning of the Lactococcus lactis ketoisovalerate decarboxylase (Kivd) specificity toward 1-pentanol synthesis was achieved via saturated mutagenesis of the key residue V461 followed by screening of the resulting alcohol spectrum.

Engineering efficient production of itaconic acid from diverse substrates in Escherichia coli.

Itaconic acid is an excellent polymeric precursor with wide range of industrial applications. Here, efficient production of itaconate from various renewable substrates was demonstrated by engineered Escherichia coli. Limitation in the itaconate precursor supply was revealed by feeding of the key intermediate citrate to the culture medium.