title: Thioredoxin-like protein TlpA from Bradyrhizobium japonicum is a reductant for the copper metallochaperone ScoI.
abstract: TlpA and ScoI of Bradyrhizobium japonicum are membrane-anchored thioredoxin-like proteins oriented towards the periplasm. TlpA is a protein-disulfide reductase. ScoI is a copper chaperone for cytochrome oxidase biogenesis. TlpA with its negative redox potential (E(o') -256 mV) was shown here to reduce oxidized ScoI, for which we determined a less negative E(o') (-160 mV). The fast forward reaction (rate constant 9.4×10(4) M(-1) s(-1)) was typical for physiologically relevant disulfide exchange reactions. A transient TlpA-ScoI heterodisulfide formed between Cys107 of TlpA's active site (C(107)XXC(110)) and Cys78 of ScoI's copper-binding site (C(74)XXXC(78)). We conclude that TlpA recycles ScoI to the dithiol form prior to metallation.
authors.affiliation: ETH Zurich, Institute of Molecular Biology and Biophysics, CH-8093 Zurich, Switzerland.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Mohorko
authors.forename: Helge K
authors.initials: HK
authors.lastname: Abicht
authors.forename: Doris
authors.initials: D
authors.lastname: Bühler
authors.forename: Rudi
authors.initials: R
authors.lastname: Glockshuber
authors.forename: Hauke
authors.initials: H
authors.lastname: Hennecke
authors.forename: Hans-Martin
authors.initials: HM
authors.lastname: Fischer
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D020369:Bradyrhizobium / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000378:metabolism; D007700:Kinetics; D056511:Metallochaperones / Q000378:metabolism*; D010084:Oxidation-Reduction; D019897:Periplasm / Q000378:metabolism; D019163:Reducing Agents / Q000378:metabolism*; D013879:Thioredoxins / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D056511:Metallochaperones; D019163:Reducing Agents; C084726:TlpA protein, Bradyrhizobium; D013879:Thioredoxins; D003576:Electron Transport Complex IV