title: Molecular characterization of the heteromeric coenzyme A-synthesizing protein complex (CoA-SPC) in the yeast Saccharomyces cerevisiae.
abstract: Coenzyme A (CoA) as an essential cofactor for acyl and acetyl transfer reactions is synthesized in five enzymatic steps from pantothenate, cysteine, and ATP. In the yeast Saccharomyces cerevisiae, products of five essential genes CAB1-CAB5 (coenzyme A biosynthesis) are required to catalyze CoA biosynthesis. In addition, nonessential genes SIS2 and VHS3 similar to CAB3 are also involved. Using epitope-tagged variants of Cab3 and Cab5, we show that both proteins cofractionate upon chromatographic separation, forming a complex of about 330 kDa. We thus systematically investigated interactions among Cab proteins. Our results show that Cab2, Cab3, Cab4, and Cab5 indeed bind to each other, with Cab3 as the sole protein, which can interact with itself and other Cab proteins. Cab3 also binds to Sis2 and Vhs3 that were previously characterized as subunits of phosphopantothenoylcysteine decarboxylase. Pantothenate kinase encoded by CAB1 as the rate-limiting enzyme of CoA biosynthesis did not interact with other Cab proteins. Mapping studies revealed that the nonconserved N-terminus of Cab3 is required for dimerization and for binding of Cab2 and Cab5. Our interaction studies confirm early reports on the existence of a CoA-synthesizing protein complex (CoA-SPC) in yeast and provide precise data on protein domains involved in complex formation.
authors.affiliation: Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt Universität Greifswald, Greifswald, Germany.
authors.forename: Judith
authors.initials: J
authors.lastname: Olzhausen
authors.forename: Tom
authors.initials: T
authors.lastname: Moritz
authors.forename: Tim
authors.initials: T
authors.lastname: Neetz
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Schüller
mesh_terms: D053898:Biosynthetic Pathways; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D003065:Coenzyme A / Q000096:biosynthesis; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D055503:Protein Multimerization; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C586670:CAB3 protein, S cerevisiae; D002352:Carrier Proteins; C019919:CoA-synthesizing protein complex; D009097:Multienzyme Complexes; D029701:Saccharomyces cerevisiae Proteins; D003065:Coenzyme A
keywords: Saccharomyces cerevisiae; biosynthesis; coenzyme A; multienzyme complex; yeast