CRYSTAL STRUCTURES OF MINER 1: THE REDOX-ACTIVE 2FE-2S PROTEIN CAUSATIVE IN WOLF

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The endoplasmic reticulum protein Miner1 is essential for health and longevity. Mis-splicing of CISD2, which codes for Miner1, is causative in Wolfram Syndrome 2 (WFS2) resulting in early onset optic atrophy, diabetes mellitus, deafness and decreased lifespan. In knock-out studies, disruption of CISD2 leads to accelerated aging, blindness and muscle atrophy. The crystal structure of the soluble region of human Miner1 was solved to a resolution of 2.1 ¿ (R-factor=17%). Although originally annotated as a zinc finger, we show that Miner1 is a homodimer harboring two redox-active 2Fe-2S clusters, indicating for the first time an association of a redox-active FeS protein with WFS2. Each 2Fe-2S cluster is bound by a rare Cys3-His motif within a 17 amino acid segment. Miner1 is the first functionally different protein that shares the NEET fold with its recently identified paralog mitoNEET, an outer mitochondrial membrane protein. Changes in the pH sensitivity of their cluster stabilities are attributed to significant differences in the electrostatic distribution and surfaces between the two proteins.