title: Transformation of a mononitrosyl iron complex to a [2Fe-2S] cluster by a cysteine analogue.
abstract: Reversible modification of iron-sulfur clusters by nitric oxide acts as a genetic switch in a group of regulatory proteins. While the conversion of [Fe-S] clusters to iron-nitrosyls has been widely studied in the past, little is known about the reverse process, the repair of [Fe-S] clusters. Reported here is a system in which a mononitrosyl iron complex (MNIC), (PPN)[Fe(S(t)Bu)3(NO)] (1), is converted to a [2Fe-2S] cluster, (PPN)2[Fe2S2(SCH2CH2C(O)OMe)4] (2). This conversion requires only the addition of a cysteine analogue, 3-mercaptomethylpropionate (MMP), at room temperature without the need for any other reagents. The identity of 2 was confirmed spectroscopically, chemically, crystallographically, and analytically. Mass spectrometry and (34)S labeling studies support that the bridging sulfides in 2 derive from the added MMP, the cysteine analogue. The NO lost during the conversion of 1 to 2 is trapped in a dinitrosyl iron side product, (PPN)[Fe(SCH2CH2C(O)OMe)2(NO)2] (4). The present system implies that MNICs are likely intermediates in the repair of NO-damaged [2Fe-2S] clusters and that cysteine is a viable molecule responsible for the destabilization of MINCs and the formation of [2Fe-2S] clusters.
authors.affiliation: Department of Chemistry, Brown University , Providence, Rhode Island 02912, United States.
authors.forename: Jessica
authors.initials: J
authors.lastname: Fitzpatrick
authors.forename: Harris
authors.initials: H
authors.lastname: Kalyvas
authors.forename: Milos R
authors.initials: MR
authors.lastname: Filipovic
authors.forename: Ivana
authors.initials: I
authors.lastname: Ivanović-Burmazović
authors.forename: John C
authors.initials: JC
authors.lastname: MacDonald
authors.forename: Jason
authors.initials: J
authors.lastname: Shearer
authors.forename: Eunsuk
authors.initials: E
authors.lastname: Kim
mesh_terms: D003545:Cysteine / Q000031:analogs & derivatives / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009589:Nitrogen Oxides / Q000737:chemistry*
chemical_list: D007506:Iron-Sulfur Proteins; D009589:Nitrogen Oxides; C073661:dinitrosyl iron complex; D007501:Iron; D003545:Cysteine