Crystal Structure of Miner1: The Redox-active 2Fe-2S Protein Causative in Wolfram Syndrome 2
[CISD2_HUMAN] Defects in CISD2 are the cause of Wolfram syndrome type 2 (WFS2) [MIM:604928]. A rare disorder characterized by juvenile-onset insulin-dependent diabetes mellitus with optic atrophy. Other manifestations include diabetes insipidus, sensorineural deafness, dementia, psychiatric illnesses. WFS2 patients additionally show a strong bleeding tendency and gastrointestinal ulceration. Diabetes insipidus may be absent.
[CISD2_HUMAN] Regulator of autophagy that contributes to antagonize BECN1-mediated cellular autophagy at the endoplasmic reticulum. Participates in the interaction of BCL2 with BECN1 and is required for BCL2-mediated depression of endoplasmic reticulum Ca(2+) stores during autophagy. Contributes to BIK-initiated autophagy, while it is not involved in BIK-dependent activation of caspases. Involved in life span control, probably via its function as regulator of autophagy. 
Publication Abstract from PubMed
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. In this work, we characterized the soluble region of human Miner1 and solved its crystal structure to a resolution of 2.1 A (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 Cys(3)-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. We report the first measurement of the redox potentials (E(m)) of Miner1 and mitoNEET, showing that they are proton-coupled with E(m) approximately 0 mV at pH 7.5. Changes in the pH sensitivity of their cluster stabilities are attributed to significant differences in the electrostatic distribution and surfaces between the two proteins. The structural and biophysical results are discussed in relation to possible roles of Miner1 in cellular Fe-S management and redox reactions.
Crystal structure of Miner1: The redox-active 2Fe-2S protein causative in Wolfram Syndrome 2.,Conlan AR, Axelrod HL, Cohen AE, Abresch EC, Zuris J, Yee D, Nechushtai R, Jennings PA, Paddock ML J Mol Biol. 2009 Sep 11;392(1):143-53. Epub 2009 Jul 4. PMID:19580816
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.