L lysine

All chemicals were purchased from Sigma‐Aldrich (Darmstadt, Germany), unless otherwise indicated. Cells were cultured at 30 °C with 200 RPM shaking in 50 mL CELLreactor™ filter top tubes (Greiner Bio‐On, Kremsmünster, Austria). Strains were grown overnight by inoculation in 5‐mL synthetic glucose media without uracil and lysine and supplemented with the dipeptide Lys‐Lys. Media were prepared by dissolving 2% w/v glucose and 0.69% w/v yeast nitrogen base (YNB) without amino acids (Formedium, Norfolk, UK). Media were supplemented with 0.19% w/v Kaiser synthetic mixture without uracil and lysine 51, that is, a mixture containing 18 mg·L⁻¹ adenine, 76 mg·L⁻¹ myo‐inositol, 8 mg·L⁻¹ para‐aminobenzoic acid, and 76 mg·L⁻¹ of all 20 standard amino acids (l‐leucine was added at 380 mg·L⁻¹) except l‐lysine (Formedium). Finally, 200 mg·L⁻¹ Lys‐Lys was added. Subcultures were grown and diluted for two to three consecutive days such that the OD₆₀₀ never exceeded 1. Cells were centrifuged at 3000 g for 5 min at 4 °C, supernatant was decanted, and cells were suspended in ice‐cold 100 mm potassium phosphate, 10 mm glucose, pH 6.0. This step was performed twice before suspension of the cells to an OD₆₀₀ of 5.