Phenotypic suppression assay shows that Tat1p and Gap1p permeases are targets of eugenol in the yeast cytoplasmic membrane.

<p>Overexpression constructs of four permeases, <i>BAP2, GAP1</i>, <i>TAT1</i> and <i>TAT2</i> were transformed separately into the <i>aro1Δ</i> strain. Transformants were grown overnight in SC-ura medium, diluted 1∶300 and then added to each well of a sterile microtiter plate with or without 0.18 mg/ml eugenol. Growth of the <i>aro1Δ</i> transformants containing the overexpression constructs were compared to one with a control plasmid by measuring the optical density of cells in each well (OD₆₀₀). The values are expressed as mean (±SD, n = 3) and significant differences between treatment and plasmid control are indicated as <i>P<0.05</i> (*) and <i>P<0.01</i> (**) based on Student T-test. Inset: eugenol is structurally similar to aromatic amino acids and is synthesized in plants via the phenylpropanoid pathway from phenylalanine.