In the context of the centenary of the restoration of diplomatic relations between France and Poland, 2019 has been declared "French-Polish Scientific Year". In this regard, this Symposium is organised to deepen and enrich cooperation between research institutes in Poland and the research centres constituting the Fédération de recherche en biologie de Toulouse (CBI and IPBS).
09:00 am - Coffee reception and registration of participants
09:30 am - Introduction to the symposium and French-Polish scientific year by Dr. Isabelle Saves, Head of international affairs
09:35 am - Lecture by Dr. Hedia Marrakchi (IPBS, CNRS-University of Toulouse - France)
10:00 am - Lecture by Dr. Przemysław Płociński (Polish Academy of Sciences, Łódź - Poland)
10:30 am - Lecture by Dr. Damian Trojanowski (University of Wrocław - Poland)
11:00 am - Lecture by Dr. Manuel Campos (LMGM-CBI, CNRS-University of Toulouse - France)
11:30 am - Lecture by Prof. Jarosław Dziadek (Polish Academy of Sciences, Łódź - Poland)
The afternoon will be dedicated to discussion with IPBS and CBI research groups and core facilities.
Contact: Hédia Marrakchi (firstname.lastname@example.org)
Note for visitors: Please come with a valid identity card
Invited speakers from Poland
An essential role of RNA degradosome complexes in shaping the transcriptome of Mycobacterium tuberculosis
The physiology of Mycobacterium tuberculosis is commonly inferred from the analysis of transcript abundance. While mechanisms of transcriptional regulation have been extensively analysed in mycobacteria, the processes that shape the transcriptome by posttranscriptional regulation, including RNA decay, are less well understood. Here, the study was set up to identify RNA binding protein factors, influencing the shape of mycobacterial transcriptome on a global scale. A modified RNA-protein crosslinking strategy coupled with high resolution mass spectrometry was used to identify RNA interacting proteins from mycobacterial cells. Unexpectedly, the RNA bound proteome was dominated by elements considered to be core degradosome components in model bacterial organisms. Next, affinity chromatography techniques were used to confirm for the first time, that the constituents of the RNA decay machinery form protein complexes in M. tuberculosis, with polynucleotide phosphorylase (PNPase) playing a central role in mycobacterial degradosome assemblies. Strains depleted of individual RNA decay ribonucleases in M. tuberculosis helped to discover massive transcriptomic rearrangements caused by depletion of PNPase. PNPase was very recently recognized as the molecular target of the first-line antituberculosis drug – Pyrazinamide and mutations in PNPase are linked with development of drug resistance, a serious problem for worldwide healthcare systems struggling with tuberculosis plague. Thus, characterisation of the function of individual RNA decay elements as well as understanding their role in the mycobacterial physiology and RNA metabolism as a complex is important for future planning of effective anti-tuberculosis treatment strategies.
Real-Time single-cell analysis of mycobacterial replisome and chromosome dynamics upon treatment with antibiotics blocking DNA replication
Spreading resistance to antibiotics and the emergence of multidrug-resistant strains have become frequent in many bacterial species, including mycobacteria. One of the factors responsible for the setback in the treatment of tuberculosis (TB) is the high population heterogeneity of mycobacterial cells. Asymmetric growth coupled with asymmetric septum placement give rise to daughter cells of unequal size and growth rate and different susceptibility to antibiotics. Here, we used a system of microfluidics, fluorescence microscopy and target-tagged fluorescent reporter strains of M. smegmatis to perform real-time monitoring of replisome and chromosome dynamics following the addition of replication-altering drugs (novobiocin, nalidixic acid and griselimycin) at the single-cell level. We found that novobiocin stalled replication forks and caused relaxation of the nucleoid, nalidixic acid triggered rapid replisome collapse and compaction of the nucleoid, and griselimycin caused replisome instability with subsequent over-initiation of chromosome replication and over-relaxation of the nucleoid. This work is an example of using a microscopy-based approach to evaluate the activity of potential replication inhibitors and provides mechanistic insights into their modes of action. Our system also enabled us to observe how the tested antibiotics affected the physiology of mycobacterial cells (i.e., growth, chromosome segregation, etc.). Because proteins involved in the DNA replication are well conserved among bacteria (including mycobacterial species), the properties of various replication inhibitors observed here in fast-growing M. smegma(s may be easily extrapolated to slow-growing pathogenic tubercle bacilli, such as M. tuberculosis.
Evaluation of putative drugs and antibiotic drug targets in tubercle bacilli
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is an intracellular pathogen claiming 1.5 million lives each year, is relatively hard to eradicate and poses a challenge for effective chemotherapy. TB treatment lasts six to 24 months depending on the drug susceptibility of the infecting strain and requires a cocktail of at least 4 drugs used simultaneously to prevent the selection of drug-resistant Mtb mutants. Treatment of tuberculosis caused by the strains resistant to at least isoniazid and rifampicin (multi drug-resistant, MDR), requires additional drugs, is often less effective, and less well tolerated. Additionally, the treatment of MDR tuberculosis is much more expensive than the standard treatment, the outcomes are several times worse with a high mortality rate (50-80%) within 4 months of diagnosis (WHO, 2014), and twice the risk of relapse after the completion of treatment.
Taking the above into account the development of the alternative medical strategies based on the new generation of drugs is desperately needed to effectively cure MDR-TB, reduce the duration of current therapies, and minimize the toxicity and cost of the antitubercular agents used.
In order to address the challenges of multi-drug resistance tuberculosis our research group (i) evaluates the potential role of the newly-discovered rpoB mutations in the development of RMP resistance, (ii) evaluates nucleic acids metabolism proteins as potential targets for antibiotics, (iii) conducts screening for potent inhibitors using various in vitro and in vivo assays, (iv) identify molecular targets for randomly selected inhibitors effective against Mtb.
09:00 - 13:00
Fernand Gallais Conference room