Dissertation / PhD Thesis/Book

PreJuSER-37440

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Molekulare Charakterisierung des Cytochrom -bc1-aa3-Superkomplexes aus Corynebacterium glutamicum

Niebisch, A. (Corresponding author)FZJ*

2003
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/91

Report No.: Juel-4032

Abstract: Spectroscopical investigations and inhibitor studies indicated a branched respiratory chain in Corynebacterium glutamicum. Electrons can be transferred to oxygen either via a cytochrome bcl complex and a aa$_{3-}$type cytochrome c oxidase or alternatively via a menaquinol oxidase of the cytochrome bd-type. The aim of this work was a molecular characterization of the postulated bc$_{1}$-aa$_{3}$-branch. The genes of the three subunits of the bcl complex (gcrCAB) and of subunits I and III of cytochrome aa$_{3}$ oxidase (ctaD and ctaE) were cloned and sequenced. Analysis of the deduced protein sequences showed a number of unusual features. The Rieske iron sulfur protein (QcrA) had three putative N-terminal transmembranhelices and cytochrome b (QcrB) possessed a large C-terminal domain consisting of approximately 130 amino acids in addition to the conserved part ofthe protein. Most remarkably, cytochrome c$_{1}$ (QcrC)contained two CXXCH motifs for covalent heme binding indicating that this protein is a diheme-cytochrome c. Inactivation of the bc$_{1}$ complex or the cytochrome aa$_{3}$ oxidase by chromosomal deletion of the qcr genes and the ctaD gene, respectively, led to strongly impaired aerobic growth an glucose minimal medium indicating that the bc$_{1}$-aa$_{3}$-pathway is the main route of respiratoon under these conditions. Cytochrome b (QcrB) and subunit I of cytochrome aa$_{3}$ oxidase (CtaD) were elongated with a C-terminal StrepTag II and purified by affmity chromatography an StrepTactin sepharose. In both cases a bc$_{1}$-aa$_{3}$-supercomplex was obtained which possessed quinol oxidase activity and therefore represented a functional association of bc$_{1}$ complex and cytochrome aa$_{3}$ oxidase. Mutation of the cysteine residues in either heme binding motifs of cytochrome c$_{l}$ (QcrC) led to a similar phenotype like deletion of the qcr genes. No c-type cytochrome could be detected in membranes of both strains and their QcrB content was strongly reduced. Obviously both heme binding motifs of QcrC are essential for activity, assembly and/or stability ofthe bc$_{1}$ complex.

Note: Record converted from VDB: 12.11.2012
Note: Düsseldorf, Univ., Diss., 2002

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Contributing Institute(s):

1. Biotechnologie 1 (IBT-1)

Research Program(s):

1. Biotechnologie (L02)

Appears in the scientific report 2003
Notes: Nachtrag

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Database coverage:

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