title: NADPH inhibits [2Fe-2S] cluster protein transfer from diabetes drug target MitoNEET to an apo-acceptor protein.
abstract: MitoNEET (mNT) is the founding member of the recently discovered CDGSH family of [2Fe-2S] proteins capable of [2Fe-2S] cluster transfer to apo-acceptor proteins. It is a target of the thiazolidinedione (TZD) class of anti-diabetes drugs whose binding modulate both electron transfer and cluster transfer properties. The [2Fe-2S] cluster in mNT is destabilized upon binding of NADPH, which leads to loss of the [2Fe-2S] cluster to the solution environment. Because mNT is capable of transferring [2Fe-2S] clusters to apo-acceptor proteins, we sought to determine whether NADPH binding also affects cluster transfer. We show that NADPH inhibits transfer of the [2Fe-2S] cluster to an apo-acceptor protein with an inhibition constant (K(i)) of 200 μm, which reflects that of NADPH concentrations expected under physiological conditions. In addition, we determined that the strictly conserved cluster interacting residue Asp-84 in the CDGSH domain is necessary for the NADPH-dependent inhibition of [2Fe-2S] cluster transfer. The most critical cellular function of NADPH is in the maintenance of a pool of reducing equivalents, which is essential to counteract oxidative damage. Taken together, our findings suggest that NADPH can regulate both mNT [2Fe-2S] cluster levels in the cell as well as the ability of the protein to transfer [2Fe-2S] clusters to cytosolic or mitochondrial acceptors.
authors.affiliation: Department of Chemistry, University of California at San Diego, La Jolla, California 92093, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Zuris
authors.forename: Syed S
authors.initials: SS
authors.lastname: Ali
authors.forename: Howard
authors.initials: H
authors.lastname: Yeh
authors.forename: Tung A
authors.initials: TA
authors.lastname: Nguyen
authors.forename: Rachel
authors.initials: R
authors.lastname: Nechushtai
authors.forename: Mark L
authors.initials: ML
authors.lastname: Paddock
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Jennings
mesh_terms: D020816:Amino Acid Motifs; D001059:Apoproteins / Q000737:chemistry*; D001665:Binding Sites; D001667:Binding, Competitive; D005288:Ferredoxins / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007004:Hypoglycemic Agents / Q000737:chemistry; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D007700:Kinetics; D024101:Mitochondrial Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D020125:Mutation, Missense; D009249:NADP / Q000737:chemistry*; D010084:Oxidation-Reduction; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D045162:Thiazolidinediones / Q000737:chemistry
chemical_list: D001059:Apoproteins; C525595:CISD1 protein, human; D005288:Ferredoxins; D007004:Hypoglycemic Agents; D007506:Iron-Sulfur Proteins; D024101:Mitochondrial Proteins; D045162:Thiazolidinediones; D009249:NADP