Home > Publications database > Regulation and assembly of the cytochrome bc1 -aa3 supercomplex in Corynebacterium glutamicum |
Book/Dissertation / PhD Thesis | FZJ-2019-03124 |
2019
Forschungszentrum Jülich GmbH Zentralbibliothek Verlag
Jülich
ISBN: 978-3-95806-416-4
Please use a persistent id in citations: http://hdl.handle.net/2128/22591 urn:nbn:de:0001-2019100943
Abstract: The synthesis of aerobic respiratory chains requires cofactors such as heme and copper and chaperones involved in the biogenesis of the enzyme complexes. The Gram-positive soil bacterium $\textit{Corynebacterium glutamicum}$ possesses a branched aerobic respiratory chain comprising, besides several dehydrogenases reducing menaquinone to menaquinol, a copper-dependent cytochrome $\textit{bc$_{1}$-aa$_{3}$}$ supercomplex and cytochrome $\textit{bd}$ quinol oxidase. The cytochrome $\textit{bc$_{1}$-aa$_{3}$}$ supercomplex is characteristic for aerobic $\textit{Actinobacteria}$ and the major generator of proton-motive force, but knowledge on its assembly or regulation is very limited. In this thesis, assembly factors involved in copper and heme insertion and regulatory proteins involved in expression control of respiratory chain components were identified and characterized. The following results were obtained: (i) Identification of the copper-deprivation stimulon led to the discovery of the two proteins Cg2699 ($\textbf{c}$opper $\textbf{t}$ransport and $\textit{i}$nsertion $\textbf{p}$rotein, CtiP) and Cg1884 (CopC). CtiP contains 16 predicted transmembrane helices and shows sequence similarity to the copper-transporter CopD and the cytochrome biogenesis chaperone CtaG. Deletion of $\textit{ctiP}$ resulted in a strong growth defect in standard glucose minimal medium (CGXII) resembling a cytochrome $\textit{aa$_{3}$}$ oxidase-deficient strain. Furthermore, the Δ$\textit{ctiP}$ strain exhibited an increased copper-tolerance, suggesting a copper transporting function. Transcriptome analysis revealed an induction of the copper-deprivation stimulon in the Δ$\textit{ctiP}$ 4 strain under copper sufficiency. CopC is a secreted protein with a C-terminal transmembrane helix and harbors a Cu(II)-binding site. Deletion of $\textit{copC}$ resulted in a growth defect in BHI complex medium and improved growth under copper excess, also suggesting an involvement in copper-transport. The lack of either CtiP or CopC prevented co-purification of the subunits of the supercomplex, indicating a crucial role of both CtiP and CopC in the correct assembly of the supercomplex. [...]
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