This title appears in the Scientific Report :
2011
Novel insights into the energy metabolism of $\textit{Corynebacterium glutamicum}$ by comprehensive analysis of mutants defective in respiration or oxidative phosphorylation
Novel insights into the energy metabolism of $\textit{Corynebacterium glutamicum}$ by comprehensive analysis of mutants defective in respiration or oxidative phosphorylation
$\textit{Corynebacterium glutamicum}$ ATCC 13032 prefers an aerobic respiratory type of energy metabolism, which involves a branched respiratory chain, terminated by a cytochrome $\textit{bc}_{1}$-$\textit{aa}_{3}$ supercomplex or by cytochrome $\textit{bd}$ oxidase, and a H$^{+}$-coupled F$_{1}$F$_...
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Personal Name(s): | Koch-Koerfges, Abigail (Correspondng author) |
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Contributing Institute: |
Biotechnologie 1; IBT-1 |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
2012
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Physical Description: |
137 S. |
Dissertation Note: |
Universtät Düsseldorf, Diss., 2011 |
ISBN: |
978-2-89336-826-6 |
Document Type: |
Book Dissertation / PhD Thesis |
Research Program: |
Biotechnologie |
Series Title: |
Schriften des Forschungszentrums Jülich. Reihe Gesundheit / Health
57 |
Subject (ZB): | |
Publikationsportal JuSER |
$\textit{Corynebacterium glutamicum}$ ATCC 13032 prefers an aerobic respiratory type of energy metabolism, which involves a branched respiratory chain, terminated by a cytochrome $\textit{bc}_{1}$-$\textit{aa}_{3}$ supercomplex or by cytochrome $\textit{bd}$ oxidase, and a H$^{+}$-coupled F$_{1}$F$_{O}$-ATP synthase. In this thesis, defined mutants of $\textit{C. glutamicum}$ defective in respiration or oxidative phosphorylation were analyzed and the following results were obtained: (i) A mutant with a deletion of the $\textit{atpBEFHAGDC}$ genes encoding F$_{1}$F$_{O}$-ATP synthase was shown to reach 47% of the growth rate and 65% of the biomass of the wild type during cultivation in glucose minimal medium. The $\Delta$F$_{1}$F$_{O}$ mutant had an increased proton motive force (pmf) which presumably resulted from an increased respiration rate and the absence of a major consumer of pmf. As the F1FO mutant gains ATP only via substrate level phosphorylation, oxidative phosphorylation is not essential for $\textit{C. glutamicum}$. (ii) While the lack of the $\textit{bd}$ oxidase in strain $\Delta \textit{cydAB}$ hardly influenced growth, absence of the $\textit{bc}_{1}$ complex in strain $\Delta \textit{qcr}$ led to reduced growth rates, cell yields and pmf. These results confirmed that the $\textit{bc}_{1}-\textit{aa}_{3}$ supercomplex is the major coupling site for pmf generation. (iii) A strain was constructed lacking both the $\textit{bc}_{1}$ complex and $\textit{bd}$ oxidase and named DOOR, which is mnemonic for “$\underline{d}$evoid $\underline{o}$f $\underline{o}$xygen $\underline{r}$espiration”. The DOOR strain showed strongly retarded growth in glucose minimal medium, which could be improved by addition of peptone. No oxygen consumption was observed for the DOOR strain, proving a dysfunctional $\textit{aa}_{3}$ oxidase in the absence of the $\textit{bc}_{1}$ complex. The pmf was reduced only about 28 - 30%, suggesting that other enzymes contribute to pmf generation in the absence of oxygen respiration, such as F$_{1}$F$_{O}$-ATP synthase. Use of F$_{1}$F$_{O}$-ATP synthase in the reverse reaction could lead to ATP deficiency. Glucose catabolism by the DOOR strain under aerobic conditions resembled that of the wild type under anaerobic conditions, in that lactate, succinate and acetate were formed as major products. The viability of the DOOR strain proves that oxygen respiration is not essential for aerobic growth of $\textit{C. glutamicum}$. (iv) A $\Delta \textit{ctaD}$ mutant missing subunit I of the $\textit{aa}_{3}$ oxidase was previously shown to lack all four subunits of the $\textit{aa}_{3}$ oxidase and in addition the diheme cytochrome $\textit{c}_{1}$ (QcrC). An increased level of thiobarbituric acid-reactive substances and a strongly disturbed pattern of fatty and mycolic acids suggested that in the absence of QcrC the Rieske iron-sulfur protein (QcrA) promotes lipid peroxidation (LPO), resulting in a very strong growth inhibition of the $\Delta \textit{ctaD}$ mutant in glucose minimal medium. These defects could be largely reversed by the addition of thiamine, which has been described as an inhibitor of LPO. |