TopoClub 2025 6ème journée de rencontre

Liste des abstracts

2. Bacterial chromatin remodeling associated with transcription-induced domains at pathogenicity Islands.

Virginia Lioy (I2BC)

Salmonella Pathogenicity Islands (SPIs) are horizontally acquired genetic elements integrated in the chromosome of Salmonella species, which allow them to infect and survive within their hosts. The nucleoid associated protein H-NS silences SPI gene transcription and this repression is counter-silenced at precise stages of the Salmonella infectious cycle. Bistable expression of the Type...

9. DNA topoisomerase I C-terminal domain is crucial for the pathogeny and stress response of adherent Invasive E. coli

Céline Borde (CIRB CDF)

Crohn's disease (CD) is a multifactorial disease characterized by chronic inflammation of the digestive tract. This inflammation leads to dysbiosis of the intestinal microbiota, resulting in abnormal colonization by proteobacteria such as invasive adherent E. coli (AIEC). These bacteria can adhere to epithelial cells, invade them, survive in macrophages and form an intracellular bacteria...

8. Dynamics of Streptomyces genome architecture and genomic island expression

Stéphanie Bury-Moné (Université Paris-Saclay - I2BC)

Streptomyces are characterized by a large linear chromosome divided into a central region harboring cores genes and two extremities enriched in poorly conserved sequences including genomic islands (GIs) encoding notably specialized metabolite biosynthetic gene clusters (SMBGCs) or prophages. The majority of these GIs remain transcriptionally silent over growth under lab conditions. We...

6. HU plays a key role in nucleoid organization and compaction in the radiation-resistant bacterium Deinococcus radiodurans

Joanna TIMMINS (Institut de Biologie Structurale, CNRS, Grenoble, France)

A major player in bacterial nucleoid organization is the histone-like HU protein. In the radiation resistant bacterium, Deinococcus radiodurans, HU is an essential protein that largely coats the genomic DNA and plays a central role in regulating the remarkable plasticity and high level of compaction of this bacterium’s nucleoid. Using conventional and super-resolution microscopy approaches,...

3. La reverse gyrase était-elle présente chez LUCA et/ou chez le dernier ancêtre commun des Asgard

Patrick FORTERRE (Institut Pasteur Université Paris-Saclay)

La reverse gyrase est systématiquement présente chez tous les organismes avec une température optimale de croissance égale ou supérieur à 80°C et systématiquement absente chez tous les organismes avec une température optimale de croissance égale ou inférieure à 55°C. Des publications récentes ont suggéré la présence de cette enzyme chez LUCA et chez le dernier ancêtre commun des archées Asgard...

1. Quantitative insights into topoisomerase activity during gene transcription

Ivan Junier (TIMC, UMR 5525, Grenoble)

While the feedback between transcription and DNA supercoiling is well understood theoretically and in vitro, it remains to be quantified in vivo. In this talk, I will present our work where we fill this gap by realizing, on a plasmid in Escherichia coli, the conceptual “twin transcriptional-loop model” that is the basis of theoretical and in vitro studies. In particular, we measured how gene...

5. Replicon dynamics during the cell cycle in Escherichia coli

Iris Veyrier (LMGM CBI)

During bacterial cell cycle, the replication of the chromosome and plasmids is followed by the segregation of each copy in daughter cells. As replication and segregation must be finely coordinated with cell division many proteins are recruited. Notably the MatP protein, and its DNA binding site matS, which participates in the positioning of the ter regions of sister chromatids at midcell; and...

10. Structural basis of DNA crossover capture by Escherichia coli DNA gyrase

Mme Marlène Vayssières (Laboratoire Citcom - UMR8038)

DNA supercoiling must be precisely regulated by topoisomerases to prevent DNA entanglement. The interaction of type IIA DNA topoisomerases with two DNA molecules, enabling the transport of one duplex through the transient double-stranded break of the other, remains elusive owing to structures derived solely from single linear duplex DNAs lacking topological constraints. Using cryo-electron...

4. The first structural observations of an XerCD-dif DNA recombinase complex

James Provan (I2BC - CNRS UMR9198)

Xer recombination is a ubiquitous process which enables the resolution of bacterial chromosome dimers at cell division. The Xer system of most bacterial species is composed of two related proteins, XerC and XerD, which are part of the wider tyrosine recombinase family with well-known enzymes such as Cre and Flp. An active Xer recombinase complex is heterotetrameric, containing two XerC units,...

7. Validation of Corynebacterium glutamicum as a surrogate for the discovery of new anti-mycobacterial compounds through the study of a well-established antibacterial target: DNA gyrase

Yaelle WORMSER (Unité des Mécanismes du Cycle Cellulaire Bactérien, Département de Biologie Structurale & Chimie, Département de Microbiologie, Institut Pasteur, CNRS UMR 3528, Université Paris Cité, Paris, France)

Despite global efforts to combat tuberculosis (TB), the latest WHO report shows a total of 1.3 million people who died from TB, including 167 000 people with HIV. TB is the leading cause of death among HIV-infected patients, and the first leading infectious killer. Worldwide, multridrug-resistant TB (MDR- TB) is a major a public health problem and security threat. In order to eradicate TB, the...