Increased production of isobutanol in yeast with reduced mitochondrial amino acid biosynthesis
View Patent ↗Yeast cells with reduced activity of certain enzymes involved in branched chain amino acid biosynthesis in yeast mitochondria are described. Target enzymes include threonine deaminase, isopropylmalate synthase, and optionally branched chain amino acid transaminase.
1. A recombinant yeast host cell which produces isobutanol and comprises mitochondria which is substantially devoid of threonine deaminase activity.
2. The yeast cell of claim 1 wherein the mitochondria is further substantially devoid of branched chain amino acid transaminase activity.
3. The yeast cell of claim 1 wherein the threonine deaminase activity is defined by the enzyme classification number EC 4.3.1.19.
4. The yeast cell of claim 1 wherein endogenous pyruvate decarboxylase activity is reduced.
5. The yeast cell of claim 2 wherein the branched chain amino acid transaminase activity is defined by the enzyme classification number EC 2.6.1.42.
6. The recombinant yeast host cell of claim 1 wherein the yeast is selected from the group consisting of Saccharomyces, Schizosaccharomyces, Hansenula, Candida, Kluyveromyces, Yarrowia and Pichia.
7. The yeast cell of claim 1 comprising a disruption in ILV1.
8. The yeast cell of claim 2 comprising a disruption in the BAT1 gene.
9. The yeast cell of claim 1 wherein the mitochondria is further substantially devoid of isopropylmalate synthase activity.
10. The yeast cell of claim 9 comprising a disruption in LEU4.