Acetyl-CoA producing enzymes in yeast

A method of identifying a heterologous polypeptide having enzymatic activity for converting pyruvate, acetaldehyde or acetate into acetyl-CoA in a cytosol of a yeast cell comprising:

• providing a mutated yeast cell, wherein said mutation comprises an inactivation of at least one gene of a pyruvate dehydrogenase (PDH) by-pass, selected from the genes encoding the enzymes pyruvate decarboxylase (PDC), acetaldehyde dehydrogenase (ALD), and acetyl-CoA synthetase (ACS);
• transforming said mutated yeast cell with an expression vector to produce a recombinant mutated yeast cell, wherein the expression vector comprises comprising at least one heterologous nucleotide sequence operably linked to a promoter functional in yeast and said heterologous nucleotide sequence encodes encoding a candidate polypeptide having potential enzymatic activity for converting pyruvate, acetaldehyde or acetate into acetyl-CoA acetyl CoA;
• testing said recombinant mutated yeast cell for its ability to grow on minimal medium containing glucose as sole carbon source and wherein the minimal medium does not contain xylose as a carbon source, and
• identifying said candidate polypeptide as a heterologous polypeptide having enzymatic activity for converting pyruvate, acetaldehyde or acetate into acetyl-CoA acetyl CoA in the cytosol of said yeast cell when growth of said cell is observed.