Universität zu Köln

Yilmaz, Cihan (2022). Molecular genetic and genomic analyses of the dual-function transcription regulator PdeL in E. coli. PhD thesis, Universität zu Köln.

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Abstract

PdeL is a transcription regulator and one of 13 phosphodiesterases in Escherichia coli K-12. Phosphodiesterases hydrolyze the ubiquitous bacterial second messenger cyclic-di-GMP and contribute to its signaling involving bacterial lifestyle and other processes. PdeL is characterized by the presence of an N-terminal FixJ/NarL-type DNA-binding domain linked to a catalytically active, cyclic-di-GMP specific, EAL-type phosphodiesterase (PDE) domain. PdeL has been shown to positively autoregulate its own expression. No further loci have yet been shown to be regulated by PdeL. In this work, I characterized PdeL as a transcriptional regulator of different loci, including the flagellar class 2 operon fliFGHIJK and sslE, encoding an extracellular metalloprotease. Repression of fliFGHIJK operon inhibits the expression of flagellar subunits needed in the early phase of flagella synthesis. As a result of repression of transcription by PdeL motility is inhibited. The DNA-binding site of PdeL at the regulatory region of fliFGHIJK overlaps with DNAbinding sites of flagellar master regulator FlhD4C2 and transcription regulator CsgD indicating that PdeL could be repressing fliFGHIJK transcription by inhibiting its activation. The expression of sslE is activated by PdeL. The metalloprotease SslE is important for infection of epithelial cells by E. coli. Regulation of sslE by PdeL indicates a role of PdeL in virulence. In addition, I describe a finding that overexpression of PdeL and other transcription regulators cause changes in nucleoid structure and affect cell division presumably by unspecific binding throughout the nucleoid. This finding is of particular relevance for the characterization of transcription regulators when physiological conditions under which they are expressed and active are yet poorly understood and plasmidic expression systems are employed.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Yilmaz, Cihan cihan1990@live.de UNSPECIFIED UNSPECIFIED
Contributors:	Contribution Name Email Censor Schnetz, Karin karin.schnetz@uni-koeln.de Censor Thormann, Kai Kai Thormann
URN:	urn:nbn:de:hbz:38-623398
Date:	2022
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Biology > Institute for Genetics
Subjects:	Life sciences
Uncontrolled Keywords:	Keywords Language Escherichia Coli; Transcription Regulation; PdeL; UNSPECIFIED
Date of oral exam:	10 December 2021
Referee:	Name Academic Title Schnetz, Karin Prof. Dr. Thormann, Kai Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/62339