Figure 2.

Two distinct Fe/S cluster biosynthetic pathways exist in mitochondria (mitochondrial NFS pathway, left) and plastid (plastidial SUF pathway, right) in Arabidopsis. Sulfur from the L-cysteine (Cys) substrate is assembled into a nascent Fe/S cluster of the scaffold proteins, and then the cluster is transferred through carrier proteins before finally being incorporated into various Fe/S apo-proteins. As examples, the Fe/S proteins of the [2Fe-2S] type and of the [4Fe-4S] type (iron ions and sulfur atoms are indicated as brown and yellow dots, respectively) are shown.