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@PHDTHESIS{Wiechert:894918,
author = {Wiechert, Johanna},
title = {{S}ilencing and counter-silencing of the {L}sr2-like
protein {C}gp{S} in $\textit{{C}orynebacterium
glutamicumt}$},
volume = {243},
school = {Universität Düsseldorf},
type = {Dissertation},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2021-03480},
isbn = {978-3-95806-569-7},
series = {Schriften des Forschungszentrums Jülich. Reihe
Schlüsseltechnologien / Key Technologies},
pages = {IV, 265 S.},
year = {2021},
note = {Universität Düsseldorf, Diss., 2020},
abstract = {Horizontal gene transfer (HGT) is a major driving force of
microbial evolution as it allows the rapid acquisition of
new genetic traits. However, foreign DNA is likely to
decrease the fitness of recipient cells by causing
detrimental effects and therefore requires stringent control
of gene expression. Hence, bacteria evolved a number of
mechanisms allowing them to discriminate between self and
non-self. Xenogeneic silencer (XS) proteins are
nucleoid-associated proteins that preferentially bind to
horizontally acquired DNA based on differences in nucleotide
composition, in particular a higher AT content. XS proteins
are widely distributed in bacteria and belong to one of the
four classes comprising the H-NS-like XS, Rok, MvaT/U-like
proteins, and Lsr2-like XS proteins. They play a predominant
role in the acquisition of novel genetic material and
oligomerization of XS proteins to higher-order nucleoprotein
complexes tightly inhibits transcription. Binding of a
transcription factor (TF) within a silenced region may
interfere with the XS-DNA complex leading to
counter-silencing and activation of gene expression.
Consequently, XS and counter-silencing facilitate the
integration of novel genetic material into host regulatory
circuits enabling the appropriate expression in response to
physiological and environmental stimuli. The aim of this
thesis was to investigate the rules underlying silencing and
counter-silencing of the medically and biotechnologically
relevant Lsr2-like proteins conserved in actinobacteria by
using CgpS from $\textit{Corynebacterium glutamicum}$ as a
model. CgpS has previously been identified as an Lsr2-like
XS, which is crucial for maintaining the lysogenic state of
an AT-rich, cryptic prophage element. In this thesis,
genome-wide bioinformatic analyses showed that CgpS
preferentially binds to long and consecutive AT-rich
stretches and that CgpS targets typically feature a distinct
drop in GC-profile close tothe transcriptional start site
(TSS). Furthermore, a sequence-specific binding motif
containing multiple A/T steps was overrepresented in CgpS
bound regions. The importance of the drop in GC-profile and
the putative binding motif for CgpS silencing was verified
by performing in vivo reporter studies with synthetic
variants of native CgpS target promoters, demonstrating that
both DNA features cooperatively support CgpS-mediated
silencing. [...]},
cin = {IBG-1},
cid = {I:(DE-Juel1)IBG-1-20101118},
pnm = {899 - ohne Topic (POF4-899)},
pid = {G:(DE-HGF)POF4-899},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
urn = {urn:nbn:de:0001-2021110919},
url = {https://juser.fz-juelich.de/record/894918},
}