title: The mitochondrial proteins AtHscB and AtIsu1 involved in Fe-S cluster assembly interact with the Hsp70-type chaperon AtHscA2 and modulate its catalytic activity.
abstract: Arabidopsis plants contain two genes coding for mitochondrial Hsp70-type chaperon-like proteins, AtHscA1 (At4g37910) and AtHscA2 (At5g09590). Both genes are homologs of the Ssq1 gene involved in Fe-S cluster assembly in yeast. Protein-protein interaction studies showed that AtHscA2 interacts with AtIsu1 and AtHscB, two Arabidopsis homologs of the Isu1 protein and the Jac1 yeast co-chaperone. Moreover, this interaction could modulate the activity of AtHscA2. In the presence of a 1:5:5 molar ratio of AtHscA2:AtIsu1:AtHscB we observed an increase in the V(max) and a decrease in the S(0.5) for ATP of AtHscA2. Furthermore, an increase of about 28-fold in the catalytic efficiency of AtHscA2 was also observed. Results suggest that AtHscA2 in cooperation with AtIsu1 and AtHscB play an important role in the regulation of the Fe-S assembly pathway in plant mitochondria.
authors.affiliation: Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina.
authors.forename: Laura
authors.initials: L
authors.lastname: Leaden
authors.affiliation: Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina.
authors.forename: Maria V
authors.initials: MV
authors.lastname: Busi
authors.affiliation: Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina. Electronic address: gomezcasati@cefobi-conicet.gov.ar.
authors.forename: Diego F
authors.initials: DF
authors.lastname: Gomez-Casati
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping
chemical_list: D029681:Arabidopsis Proteins; C000599493:HscA2 protein, Arabidopsis; C546127:HscB protein, Arabidopsis; C493877:ISU1 protein, A thaliana; D024101:Mitochondrial Proteins
keywords: Arabidopsis; Fe–S clusters; Hsp70-like; Mitochondria