title: L-galactono-1,4-lactone dehydrogenase (GLDH) forms part of three subcomplexes of mitochondrial complex I in Arabidopsis thaliana.
abstract: L-galactono-1,4-lactone dehydrogenase (GLDH) catalyzes the terminal step of the Smirnoff-Wheeler pathway for vitamin C (l-ascorbate) biosynthesis in plants. A GLDH in gel activity assay was developed to biochemically investigate GLDH localization in plant mitochondria. It previously has been shown that GLDH forms part of an 850-kDa complex that represents a minor form of the respiratory NADH dehydrogenase complex (complex I). Because accumulation of complex I is disturbed in the absence of GLDH, a role of this enzyme in complex I assembly has been proposed. Here we report that GLDH is associated with two further protein complexes. Using native gel electrophoresis procedures in combination with the in gel GLDH activity assay and immunoblotting, two mitochondrial complexes of 470 and 420 kDa were identified. Both complexes are of very low abundance. Protein identifications by mass spectrometry revealed that they include subunits of complex I. Finally, the 850-kDa complex was further investigated and shown to include the complete "peripheral arm" of complex I. GLDH is attached to a membrane domain, which represents a major fragment of the "membrane arm" of complex I. Taken together, our data further support a role of GLDH during complex I formation, which is based on its binding to specific assembly intermediates.
authors.affiliation: Institut für Pflanzengenetik, Abteilung Pflanzenproteomik, Universität Hannover, Herrenhäuser Str. 2, 30419 Hannover, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Schertl
authors.forename: Stephanie
authors.initials: S
authors.lastname: Sunderhaus
authors.forename: Jennifer
authors.initials: J
authors.lastname: Klodmann
authors.forename: Gustavo E Gergoff
authors.initials: GE
authors.lastname: Grozeff
authors.forename: Carlos G
authors.initials: CG
authors.lastname: Bartoli
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Braun
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001205:Ascorbic Acid / Q000096:biosynthesis; D042967:Electron Transport Complex I / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000201:enzymology* / Q000235:genetics; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary
chemical_list: D029681:Arabidopsis Proteins; D024101:Mitochondrial Proteins; D044925:Oxidoreductases Acting on CH-CH Group Donors; C093910:galactonolactone dehydrogenase; D042967:Electron Transport Complex I; D001205:Ascorbic Acid