title: Sulfurtransferase and thioredoxin specifically interact as demonstrated by bimolecular fluorescence complementation analysis and biochemical tests.
abstract: Sulfurtransferases (Strs) and thioredoxins (Trxs) are members of large protein families. Trxs are disulfide reductases and play an important role in redox-related cellular processes. They interact with a broad range of proteins. Strs catalyze the transfer of a sulfur atom from a suitable sulfur donor to nucleophilic sulfur acceptors in vitro, but the physiological roles of these enzymes are not well defined. Several studies in different organisms demonstrate protein-protein interactions of Strs with members of the Trx family. We are interested in investigating the specificity of the interaction between Str and Trx isoforms. In order to use the bimolecular fluorescence complementation (BiFC), several Str and Trx sequences from Arabidopsis thaliana were cloned into the pUC-SPYNE and pUC-SPYCE split-YFP vectors, respectively. Each couple of plasmids containing the sequences for the putative interaction partners were transformed into Arabidopsis protoplasts and screened using a confocal laser scanning microscope. Compartment- and partner-specific interactions could be observed in transformed protoplasts. Replacement of cysteine residues in the redox-active site of Trxs abolished the interaction signal. Therefore, the redox site is not only involved in the redox reaction but also responsible for the interaction with partner proteins. Biochemical assays support a specific interaction among Strs and certain Trxs. Based on the results obtained, the interaction of Strs and Trxs indicates a role of Strs in the maintenance of the cellular redox homeostasis.
authors.affiliation: Institute of Botany, Leibniz University Hannover, Herrenhäuserstr. 2, D-30419 Hannover, Germany.
authors.forename: Melina
authors.initials: M
authors.lastname: Henne
authors.affiliation: University Osnabrück, Department for Plant Physiology, Barbarastraße 11, D-49076 Osnabrück, Germany.
authors.forename: Nicolas
authors.initials: N
authors.lastname: König
authors.affiliation: Institute of Botany, Leibniz University Hannover, Herrenhäuserstr. 2, D-30419 Hannover, Germany.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Triulzi
authors.affiliation: Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente, Università degli Studi di Milano, Via Celoria, 2, 20133 Milano, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Baroni
authors.affiliation: Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente, Università degli Studi di Milano, Via Celoria, 2, 20133 Milano, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Forlani
authors.affiliation: University Osnabrück, Department for Plant Physiology, Barbarastraße 11, D-49076 Osnabrück, Germany.
authors.forename: Renate
authors.initials: R
authors.lastname: Scheibe
authors.affiliation: Institute of Botany, Leibniz University Hannover, Herrenhäuserstr. 2, D-30419 Hannover, Germany.
authors.forename: Jutta
authors.initials: J
authors.lastname: Papenbrock
keywords: Arabidopsis thaliana; Bimolecular fluorescence complementation; Protein interaction; Str(s), sulfurtransferase(s); Thioredoxin; Trx(s), thioredoxin(s); YFP, yellow fluorescent protein