Fep1 is an iron-responsive GATA-type transcriptional repressor present in numerous fungi. The DNA-binding domain of this protein is characterized by the presence of two zinc fingers of the Cys₂-Cys₂ type and a Cys-X₅-Cys-X₈-Cys-X₂-Cys motif located between the two zinc fingers, that is involved in binding of a [2Fe-2S] cluster. In this work, biophysical characterization of the DNA-binding domain of Pichia pastoris Fep1 and of the complex of the protein with cognate DNA has been undertaken. The results obtained by analytical ultracentrifugation sedimentation velocity, small-angle X-ray scattering and differential scanning calorimetry indicate that Fep1 is a natively unstructured protein that is able to bind DNA forming 1:1 and 2:1 complexes more compact than the individual partners. Complex formation takes place independently of the presence of a stoichiometric [2Fe-2S] cluster, suggesting that the cluster may play a role in recruiting other protein(s) required for regulation of transcription in response to changes in intracellular iron levels.

Fep1 是一种铁反应性 GATA 型转录抑制因子，存在于多种真菌中。该蛋白质的 DNA 结合域的特征在于存在两个 Cys ₂ -Cys ₂型锌指和位于两个锌指之间的Cys-X ₅ -Cys-X ₈ -Cys-X ₂ -Cys 基序，这涉及 [2Fe-2S] 簇的结合。在这项工作中，毕赤酵母DNA 结合域的生物物理表征Fep1 和蛋白质与同源 DNA 的复合物的研究已经进行。通过分析超速离心沉降速度、小角度 X 射线散射和差示扫描量热法获得的结果表明，Fep1 是一种天然的非结构化蛋白质，能够与 DNA 结合形成 1:1 和 2:1 复合物，比单个伴侣更紧凑。复合物的形成与化学计量的 [2Fe-2S] 簇的存在无关，这表明该簇可能在招募其他蛋白质方面发挥作用，这些蛋白质是响应细胞内铁水平变化而调节转录所需的。