Book/Dissertation / PhD Thesis

FZJ-2020-05065

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Novel insights into the transcriptional regulation of cell division in Corynebacterium glutamicum

Kraxner, K. (Corresponding author)FZJ*

2021
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-560-4

Please use a persistent id in citations: http://hdl.handle.net/2128/28619  urn:nbn:de:0001-2021100106

Abstract: In the first part of this doctoral thesis the transcriptional regulation of the odhI gene (cg1630)of Corynebacterium glutamicum was analyzed. OdhI in its unphoshorylated state functions asinhibitor of the 2-oxoglutarate dehydrogenase complex (ODHC) by binding to the OdhAsubunit. Phosphorylation of OdhI by serine/threonine protein kinases abolishes this effect.Inhibition of ODHC activity by OdhI was shown to be crucial for overproduction and secretionof L-glutamate, which is used as a flavour enhancer. Since downstream of odhI two genespresumably encoding transcriptional regulators (cg1631 and cg1633) are located, it wasspeculated that these could be involved in transcriptional regulation of odhI. However,transcriptome analysis of deletion mutants lacking cg1631 or cg1633 and DNA affinitychromatography with the odhI promoter did not support this hypothesis. Furthermore, no otherpotential transcriptional regulators of odhI could be identified. Thus, there is currently noevidence for transcriptional regulation of odhI.The second part of this thesis addresses the regulation of cytokinesis in C. glutamicum. Incontrast to e.g. Escherichia coli and Bacillus subtilis, knowledge about regulators of cytokinesisin Actinobacteria is very limited. In this study, the so far uncharacterized Cg1631 protein wasdiscovered to be a transcriptional regulator of the ftsZ gene in C. glutamicum encoding the keyplayer of bacterial cell division. Therefore, Cg1631 was named FtsR, standing for FtsZregulator. Both deletion and overexpression of ftsR caused growth defects and an altered cellmorphology, emphasizing an important function of FtsR in cell division or cell wall synthesis.The wild-type phenotype could be restored by plasmid-based complementation. Chromatinaffinity purification with subsequent next generation sequencing (ChAP-Seq) identified a regionin the ftsZ promoter as a major FtsR binding site, but revealed also additional potential targetgenes. With the ChAP-Seq results a putative DNA-binding motif could be identified for FtsR.Transcriptional activation of ftsZ expression by FtsR was underlined by DNA microarrayexperiments, electrophoretic mobility shift assays (EMSAs), and reporter gene studies.Analysis of strains expressing ftsZ under control of the gluconate-inducible gntK promoterrevealed that the phenotype of the ftsR mutant is not solely caused by reduced ftsZexpression but involves additional factors. In summary, FtsR was identified as the firsttranscriptional regulator of ftsZ in C. glutamicum. Furthermore, since FtsR and its DNA-bindingsite in the promoter region of ftsZ are highly conserved in Actinobacteria, it can be assumedthat this regulatory mechanism is also relevant for the control of cell division in relatedActinobacteria. This makes FtsR a promising target for the development of new antimicrobialdrugs against pathogenic relatives of C. glutamicum

Note: Biotechnologie 1
Note: Dissertation, Heinrich-Heine-Universität Düsseldorf, 2020

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Contributing Institute(s):

1. Biotechnologie (IBG-1)

Research Program(s):

1. 581 - Biotechnology (POF3-581) (POF3-581)

Appears in the scientific report 2020

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