Fig. 5

Schematic diagram of TCA cycle, GABA shunt and malate-aspartate shuttle. The biosynthetic pathways of the amino acids with different color backgrounds were reinforced by gene overexpression, leading to different performance of glucoamylase production. The metabolic enzymes (EC numbers) and the encoding genes overexpressed in this study are shown in red. Amino acids in different color backgrounds represent the different glucoamylase production performance of the corresponding overexpression mutants (Table 1) in shake flasks (Red background means the reinforcement of synthetic pathway of this amino acid increased the glucoamylase production in the corresponding mutant compared to CBS 513.88; blue background means glucoamylase production decreased in the corresponding mutant; orange background means the corresponding mutants perform similar glucoamylase production with CBS 513.88). 3PG 3-phosphoglycerate, PEP phosphoenolpyruvate. PYR-cyt cytosolic pyruvate, PYR-mito mitochondrial pyruvate, AcCoA acetyl-CoA, CIT citrate, IsCIT isocitrate, AKG 2-oxoglutarate. SUCCoA succinyl-CoA, SUC succinate, FUM fumarate, MAL-mito mitochondrial malate, OAA-mito mitochondrial oxaloacetate, OAA-cyt cytosolic oxaloacetate, MAL-cyt cytosolic malate, GABA 4-Aminobutanoate, SAA Succinate-semialdehyde, Ala alanine, Glu glutamate, Ser serine, Gly glycine, Asp-cyt cytosolic aspartate, Asp-mito mitochondrial aspartate