You isolated a mutant that does not grow on glucose as the sole carbon source. However, the mutant does grow on glucose when supplemented with succinate, fumarate, or malate. An examination of the broken cell extract reveals that all the TCA cycle intermediates are present. Considering what you know about the cell's need for essential precursors and how the central metabolic processes integrate with each other, what do you hypothesize the metabolic defect is in this mutant?