2.A.5.1.22
Zinc (ZrfC) transporter of 522 aas and 9 TMSs in a 1 (N-terminal) + 3 (central; residues 200 - 300) + 5 TMSs (C-terminal).  Aspergillus fumigatus, one of the most widespread opportunistic human fungal pathogens, adapts to zinc limitation by secreting a 310 amino acid Aspf2 zincophore, able to specifically bind Zn²⁺ and deliver it to ZrfC. Garstka et al. 2022 focused on the thermodynamics of Zn²⁺ complexes with unstructured regions of Aspf2; basing on a variety of spectrometric and potentiometric data, they show that the C-terminal part has the highest Zn(II)-binding affinity among the potential binding sites, and Ni²⁺ does not compete with Zn²⁺ binding to this region. The 14 amino acid Aspf2 C-terminus coordinates Zn²⁺ via two Cys thiolates and two His imidazoles (Garstka et al. 2022). The Aspf2 zincophore protein is a member of the Asp F2 family (TC# 8.A.190).