L-galactono-1,4-lactone dehydrogenase (GLDH) forms part of three subcomplexes of mitochondrial complex I in Arabidopsis thaliana

SCHERTL, PETER; SUNDERHAUS, STEPHANIE; KLODMANN, JENNIFER; GERGOFF GROZEFF, GUSTAVO; BARTOLI, CARLOS GUILLERMO; BRAUN, HANS-PETER

JOURNAL OF BIOLOGICAL CHEMISTRY

AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Lugar: Bethesda, Maryland; Año: 2012 vol. 287 p. 14412 - 14419

0021-9258

L-Galactono-1,4-lactone dehydrogenase (GLDH) catalyzesthe terminal step of the Smirnoff-Wheeler pathway for vitaminC (L-ascorbate) biosynthesis in plants. A GLDH in gel activityassay was developed to biochemically investigate GLDH localizationin plant mitochondria. It previously has been shown thatGLDH forms part of an 850-kDa complex that represents aminor form of the respiratory NADH dehydrogenase complex(complex I). Because accumulation of complex I is disturbed inthe absence of GLDH, a role of this enzyme in complex I assemblyhas been proposed. Here we report that GLDH is associatedwith two further protein complexes. Using native gel electrophoresisprocedures in combination with the in gelGLDHactivityassay and immunoblotting, two mitochondrial complexes of470 and 420 kDa were identified. Both complexes are of very lowabundance. Protein identifications by mass spectrometryrevealed that they include subunits of complex I. Finally, the850-kDa complex was further investigated and shown to includethe complete “peripheral arm” of complex I. GLDH is attachedto a membrane domain, which represents a major fragment ofthe “membrane arm” of complex I. Taken together, our datafurther support a role of GLDH during complex I formation,which is based on its binding to specific assembly intermediates.