Computational Studies of the Dynamics of the Human Iron Exporter Ferroportin: Insight into the Role of Crucial Residues Involved in Pathogenic Mutations in the Transport Mechanism

Ferroportin (FPN/SLC40A1), the only known human iron exporter, plays a key role in iron homeostasis through an alternating access mechanism involving inward-open, occluded, and outward-open conformations. Pathogenic FPN mutations cause Hereditary hemo-chromatosis type 4, an autosomal dominant iron overload disease characterized by ear-ly-onset anemia, hepatic fibrosis, and diabetes. This disease can be further categorized into two subtypes: Ferroportin disease, or Hereditary hemochromatosis type 4A, characterized by low transferrin saturation (TSAT) and iron overload predominantly in Kupffer cells, and “SLC40A1-HC”, or Hereditary hemochromatosis type 4B, defined by high TSAT and iron overload in hepatocytes. However, the structural and functional characteristics gov-erning FPN's conformational transitions and their relationship to pathogenic mutations remain poorly understood. Therefore, we conducted comprehensive modelling and molec-ular dynamics studies to investigate the conformational states of the transporter and ana-lyse the molecular basis of disease-causing mutations. Our analysis revealed distinct dy-namic properties across FPN conformations, with inward-open and outward-open states displaying stable protein cores surrounded by dynamic peripheral regions, contrasting sharply with the occluded conformation. We observed significant differences in the most stable interactions established between the two lobes across the three conformational states, enabling identification of key residues involved in FPN conformational changes and iron transport. These findings were interpreted in the context of known pathogenic mutations to assess their potential effects on protein stability and transport mechanism. This approach provides crucial insights into the molecular determinants of FPN function and dysfunction, offering a foundation for understanding how specific mutations disrupt normal iron export and lead to Hereditary hemochromatosis. The identification of con-formationally important residues enhances our understanding of FPN's transport mecha-nism and provides a framework for interpreting the pathological consequences of genetic variants in iron metabolism disorders.