Typologie d'actualités: CBM

When a non-conserved protein domain becomes essential

Rho-dependent termination of transcription is a critical regulatory mechanism specific to bacteria. In a subset of species including most Actinobacteria and Bacteroidetes, the Rho factor contains a large, poorly conserved N-terminal insertion domain (NID) of cryptic function. Through the first characterization of an actinobacterial Rho factor containing a very large NID (~40% of total mass), we show that such a non-conserved protein domain can be essential for activity. Without NID, the Rho factor of Bacteroides fragilis (BfRho) indeed cannot induce transcription termination and displays a reduced affinity for RNA. Intriguingly, the presence of a NID in BfRho is not correlated to the lack of residues or motifs deemed essential in NID-less Rho factors from evolutionary distinct species. The NID requirement is probably linked to the coevolution of partner feature(s) such as lineage-specific RNA polymerase domains and/or low G+C content of the B. fragilis transcriptome. Our data thus highlight that ‘essential function’ does not always rhyme with ‘structural conservation’.

Simon I., Delaleau M., Schwartz A., Boudvillain M.
A Large Insertion Domain in the Rho Factor From a Low G + C, Gram-negative Bacterium is Critical for RNA Binding and Transcription Termination Activity
Journal of Molecular Biology (2021) 433 (15) 167060 - Doi : 10.1016/j.jmb.2021.167060




Biodiversity skepticism?

Biodiversity skepticism?

Based on analysis of time series of abundances of insect species in the United States, Crossley et al. reported in Nature Ecology & Evolution (August 2020) that there is no evidence of a global decline in insect abundance or diversity in the United States, this for both natural and anthropogenic sites. Their study described the apparent robustness of insect populations in the U.S. as reassuring, in contrast to recent studies reporting dramatic declines in their abundance around the world.

However, a multidisciplinary consortium including researchers from INRAE, the University of Rennes and CNRS identified major problems in the Crossley et al. paper concerning: 1) statistical analysis and 2) inconsistencies in data selection. The consortium demonstrates, in a commentary published in Nature Ecology & Evolution Desquilbet et al. , that these biases call into question the conclusions of Crossley et al.

This is the second time (see here) that a high-ranking publication downplaying insect declines has been subject to methodological criticisms. These studies raise the question of a "biodiversity-skepticism" within the scientific community. In order to implement an appropriate protection of biodiversity, public decision-makers need an informed diagnosis that is not clouded by biased studies which slow down decision-making.

Reference :
Desquilbet M, Cornillon PA, Gaume L & Bonmatin JM (2021)
Matters arising: Adequate statistical modelling and data selection are essential when analysing abundance and diversity trends
Nature Ecology & Evolution doi : https://www.nature.com/articles/s41559-021-01427-x

J.-M. Bonmatin co-author of an article in One Health (18 March 2021)

The “One Health” concept links environmental, animal (wild & livestock) and human health. It is increasingly being argued (e.g. Covid-19) and is now essential for the preservation of ecosystems and public health. Researchers from the universities of Leuven (BE), Sorbonne-CNRS-IRD-INRAE-UPEC (FR), CARI (BE), FNOSAD (FR) and the Centre for Molecular Biophysics (CNRS), have applied this concept to the case of biocides and veterinary products (including pesticides) that are used to treat livestock and that impact pollinators. These researchers have shown that these "multi-use substances" present (among other things) proven risks for bees and consequently need to be better assessed before being placed on the market. This work was initiated at the CBM in 2019: see here & here (Italian).

Reference :     Mahefarisoa KL, Simon Delso N, Zaninotto V, Colin ME & Bonmatin JM (2021) The Threat of Veterinary Medicinal Products and Biocides on Pollinators: A One Health Perspective, One Health, https://doi.org/10.1016/j.onehlt.2021.100237

 




SFNano Webinar – March 31st, 2021

Free Webinar "mRNA Lipid Nanoparticle formulations for mRNA-vaccines"

March 31st, 2021 3:30 – 6:00 pm (Paris Time Zone / CET)

MRNA vaccines have experienced an unprecedented burst  in basic and clinical research. These vaccines were among the first available vaccines to fight the Covid-19 pandemic and they demonstrated the potency and versatility of mRNA technology to protect against infectious disease. As this new delivery technology is going to be applied to hundreds of millions of people in the European Community and around the world, this webinar will present the key features of lipid nanoparticles (LNPs) used for the COVID-19 mRNA vaccine and will draw first lessons learned for further vaccine development and beyond for new mRNA therapies. Find out more.

Online registration

 




Neonicotinoids

A scientific article linking the contamination of soils by neonicotinoid pesticides and their presence in hair of people in the Philippines has just been published by Jean-Marc Bonmatin et al. (2020) in the journal Science of the Total Environment. This article is part of researches carried out on human health by the Task Force on Systemic Pesticides, which brings together more than sixty independent researchers (www.tfsp.info & Facebook TFSP). This article also sheds light on the exposure of populations, particularly in the context of the possible reintroduction of neonicotinoids for sugar beet in France.

This article is highlighted by the CNRS chemistry institute.

Detection of amyloid peptides: biomarkers for Alzheimer’s Disease and Diabetes

Metal chelates targeted to amyloid peptides are widely explored as diagnostic tools or therapeutic agents for amyloidogenic diseases. For example, gadolinium complexes can be used as MRI probes, while radiocomplexes (64Cu, 99mTc, etc) can be exploited for nuclear imaging. Other metal complexes capable of preventing aggregate formation are proposed to derive therapeutic strategies.

All these molecules are amphiphilic, composed of a hydrophilic part (containing the metal) and a hydrophobic one (capable of targeting the amyloid aggregates). This particular structure enables the formation of micelles in solution.

The groups of CBM and LCC (Toulouse) have found that this micellisation property has drastic and unexpected consequences on their ability to recognize amyloid peptides and a high impact on their in vivo biodistribution.

The researchers have developed a novel probe with nanomolar affinity towards Aβ and amylin, biomarkers of Alzheimer’s Disease and Ddiabetes, respectively.

This exceptional affinity for a metal complex is only obtained if the complex is present as “single molecule”. Once in the micellar form, this affinity drops by 1000-fold.

These results have a direct consequence for the design of novel imaging and therapeutic probes for amyloidogenic pathologies.

See the article