Increased Production of Isobutanol in Yeast with Reduced Mitochondrial Amino Acid Biosynthesis

Abstract

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 - 15 . (canceled) 
     
     
         16 . A recombinant yeast host cell which produces isobutanol and comprises mitochondria which is substantially devoid of branched chain amino acid transaminase activity. 
     
     
         17 . The recombinant yeast host cell of  claim 16 , wherein the mitochondria is further substantially devoid of isopropylmalate synthase activity. 
     
     
         18 . The recombinant yeast host cell of  claim 17 , wherein the mitochondria is further substantially devoid of threonine deaminase activity. 
     
     
         19 . The recombinant yeast cell of  claim 16 , wherein the branched chain amino acid transaminase activity is defined by the enzyme classification number EC 2.6.1.42. 
     
     
         20 . The recombinant yeast cell of  claim 17 , wherein the branched chain amino acid transaminase activity is defined by the enzyme classification number EC 2.6.1.42. 
     
     
         21 . The recombinant yeast cell of  claim 18 , wherein the branched chain amino acid transaminase activity is defined by the enzyme classification number EC 2.6.1.42. 
     
     
         22 . The recombinant yeast host cell of  claim 17 , wherein the isopropylmalate synthase activity is defined by the enzyme classification number EC 2.3.3.13. 
     
     
         23 . The recombinant yeast host cell of  claim 18 , wherein the isopropylmalate synthase activity is defined by the enzyme classification number EC 2.3.3.13. 
     
     
         24 . The recombinant yeast host cell of  claim 18 , wherein the threonine deaminase activity is defined by the enzyme classification number EC 4.3.1.19 
     
     
         25 . The recombinant yeast cell of  claim 16 , wherein the yeast cell comprises a disruption in a BAT1 gene. 
     
     
         26 . The recombinant yeast cell of  claim 17 , wherein the yeast cell comprises a disruption in a LEU4 gene. 
     
     
         27 . The recombinant yeast cell of  claim 18 , wherein the yeast cell comprises a disruption in a ILV1 gene. 
     
     
         28 . The recombinant yeast cell of  claim 18 , wherein the yeast cell comprises disruptions in a BAT1 gene, a LEU4 gene, and an ILV1 gene. 
     
     
         29 . The recombinant yeast cell of  claim 16 , wherein the recombinant yeast cell further comprises reduced or eliminated endogenous pyruvate decarboxylase activity. 
     
     
         30 . The recombinant yeast cell of  claim 17 , wherein the recombinant yeast cell further comprises reduced or eliminated endogenous pyruvate decarboxylase activity. 
     
     
         31 . The recombinant yeast cell of  claim 18 , wherein the recombinant yeast cell further comprises reduced or eliminated endogenous pyruvate decarboxylase activity. 
     
     
         32 . The recombinant yeast cell of  claim 16 , wherein the yeast is selected from the group consisting of  Saccharomyces, Schizosaccharomyces, Hansuela, Candida, Kluveromyces, Yarrowia , and  Pichia.    
     
     
         33 . A method of producing isobutanol comprising growing a recombinant yeast cell of  claim 16 , wherein the recombinant yeast cell is grown under conditions wherein isobutanol is produced. 
     
     
         34 . A method of producing isobutanol comprising growing a recombinant yeast cell of  claim 17 , wherein the recombinant yeast cell is grown under conditions wherein isobutanol is produced. 
     
     
         35 . A method of producing isobutanol comprising growing a recombinant yeast cell of  claim 18 , wherein the recombinant yeast cell is grown under conditions wherein isobutanol is produced.