Activation of the heterodimeric central complex SoxYZ of chemotrophic sulfur oxidation is linked to a conformational change and SoxY-Y interprotein disulfide formation.
The central protein of the four component sulfur oxidizing (Sox) enzyme system of Paracoccus pantotrophus, SoxYZ, carries at the SoxY subunit the covalently bound sulfur substrate which the other three proteins bind, oxidize, and release as sulfate. SoxYZ of different preparations resulted in different specific thiosulfate-oxidizing activities of the reconstituted Sox enzyme system. From these preparations SoxYZ was activated up to 24-fold by different reductants with disodium sulfide being the most effective and yielded a uniform specific activity of the Sox system. The activation comprised the activities with hydrogen sulfide, thiosulfate, and sulfite. Sulfide-activation decreased the predominant beta-sheet character of SoxYZ by 4%, which caused a change in its conformation as determined by infrared spectroscopy. Activation of SoxYZ by sulfide exposed the thiol of the C-terminal Cys-138 of SoxY as evident from alkylation by 4-acetamido-4'-maleimidylstilbene-2,2'-disulfonic acid. Also, SoxYZ activation enhanced the formation of the Sox(YZ)2 heterotetramer as evident from density gradient gel electrophoresis. The tetramer was formed due to an interprotein disulfide between SoxY to yield a SoxY-Y dimer as determined by combined high pressure liquid chromatography and mass spectrometry. The significance of the conformational change of SoxYZ and the interprotein disulfide between SoxY-Y is discussed.
Quentmeier
Armin
A
Lehrstuhl für Technische Mikrobiologie, Fachbereich Bio- und Chemieingenieurwesen, Universität Dortmund, Emil-Figge-Strasse 66, D-44221 Dortmund, Germany.
Janning
Petra
P
Hellwig
Petra
P
Friedrich
Cornelius G
CG
D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry*; D003545:Cysteine / Q000378:metabolism; D019281:Dimerization; D004220:Disulfides / Q000378:metabolism*; D004789:Enzyme Activation; D008954:Models, Biological; D008968:Molecular Conformation; D009097:Multienzyme Complexes; D010084:Oxidation-Reduction; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000737:chemistry* / Q000378:metabolism*; D042084:Paracoccus pantotrophus / Q000201:enzymology; D011487:Protein Conformation; D019704:Protein Disulfide-Isomerases; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D017550:Spectroscopy, Fourier Transform Infrared; D013267:Stilbenes; D013451:Sulfonic Acids; D013455:Sulfur / Q000378:metabolism; D019885:Sulfur Group Transferases / Q000737:chemistry* / Q000378:metabolism*; D013885:Thiosulfates / Q000378:metabolism
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004220:Disulfides; D009097:Multienzyme Complexes; D021122:Protein Subunits; D013267:Stilbenes; D013451:Sulfonic Acids; D013885:Thiosulfates; C079532:4-acetamido-4'-maleimidylstilbene-2,2'-disulfonic acid; D013455:Sulfur; D050862:Oxidoreductases Acting on Sulfur Group Donors; C413329:SoxZ protein, Paracoccus pantotrophus; D019885:Sulfur Group Transferases; D019704:Protein Disulfide-Isomerases; D003545:Cysteine