title: Structural and functional studies of the mitochondrial cysteine desulfurase from Arabidopsis thaliana.
abstract: AtNfs1 is the Arabidopsis thaliana mitochondrial homolog of the bacterial cysteine desulfurases NifS and IscS, having an essential role in cellular Fe-S cluster assembly. Homology modeling of AtNfs1m predicts a high global similarity with E. coli IscS showing a full conservation of residues involved in the catalytic site, whereas the chloroplastic AtNfs2 is more similar to the Synechocystis sp. SufS. Pull-down assays showed that the recombinant mature form, AtNfs1m, specifically binds to Arabidopsis frataxin (AtFH). A hysteretic behavior, with a lag phase of several minutes, was observed and hysteretic parameters were affected by pre-incubation with AtFH. Moreover, AtFH modulates AtNfs1m kinetics, increasing V(max) and decreasing the S(0.5) value for cysteine. Results suggest that AtFH plays an important role in the early steps of Fe-S cluster formation by regulating AtNfs1 activity in plant mitochondria.
authors.affiliation: Centro de Estudios Fotosintéticos y Bioquímicos, Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina.
authors.forename: Valeria R
authors.initials: VR
authors.lastname: Turowski
authors.forename: Maria V
authors.initials: MV
authors.lastname: Busi
authors.forename: Diego F
authors.initials: DF
authors.lastname: Gomez-Casati
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013437:Carbon-Sulfur Lyases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008928:Mitochondria / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D016415:Sequence Alignment
chemical_list: D029681:Arabidopsis Proteins; C518592:FH protein, Arabidopsis; D024101:Mitochondrial Proteins; D013437:Carbon-Sulfur Lyases; C080546:cysteine desulfurase