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. 2022 Oct 12;9:1034453. doi: 10.3389/fmolb.2022.1034453

FIGURE 2.

FIGURE 2

Structural models of the FeS cluster scaffold and its complex with Hsc20. (A) Cartoon depicting key structural elements of FeS cluster loaded (yellow/red balls) Isu/IscU scaffold and homology model of S. cerevisiae Isu1 with bound FeS cluster based on the crystal structure of FeS cluster bound IscU from Aquifex aeolicus (PDB ID: 2Z7E) at left and right, respectively. Insert within the circle is the structure tilted 90° to visualize the three Cys residues (yellow) that coordinate a 2Fe-2S cluster (yellow/red balls). LPPVK sequence (green) localized on a loop prior to C-terminal helix 5 (red) is the binding site for Hsp70. Hot spot residues involved in the Isu1 interactions with both Hsc20 and cysteine desulfurase Nfs1 are indicated (cyan). Note: the Hsc20 and Hsp70 binding sites on Isu1 do not overlap. (B) Cartoon representing J-domain protein Hsc20 in complex with Isu/IscU and structural model of the Hsc20 of S. cerevisiae (PDB ID: 3UO2 and 3UO3) in complex with Isu1 at left and right, respectively. Hsc20 is a simple JDP consisting of the N-terminal J-domain (dark cyan) with HPD motif (magenta) and C-terminal Isu binding domain, IBD (light cyan), which interacts with Isu via a contact surface involving hot spot residues (orange).