Biology subjects

Jacquier, H.

Publications and source records attributed to Jacquier, H..

3 recordsLinked to original sources

bioRxiv2023

The panC-encoded pantothenate synthetase to tackle carbapenem-resistant OprD Pseudomonas aeruginosa mutant revealed through Tn-Seq

For the World Health Organization, carbapenem-resistant Pseudomonas aeruginosa is a critical priority for which new antimicrobial drugs are needed. Consequently, understanding the underlying mechanisms of resistant bacteria infection will enable the identification of new therapeutic targets. Loss of the OprD porin is the main determinant of resistance to the last resort carbapenem antibiotics and has been described to enhance fitness in vivo and virulence. Transposon sequencing is a high-throughput sequencing technique that makes it possible to identify essential genes (EGs) that may turn out to be therapeutic targets. However, such a strategy has not yet been used for OprD-deficient P. aeruginosa. In this study, we identified the EGs specific to PA14 OprD mutant for LB growth and we established a list of 30 EGs among these, we highlighted the panC gene encoding pantothenate synthetase as a promising target. Using CRISPRi, we confirmed that silencing panC reduced LB growth, and decreased sigX expression, whose overexpression is associated with membrane fluidity, as well as the expression of genes involved in the fatty acid synthesis (FAS). Taking into account the weakness of PA14 OprD mutant due to an altered membrane consecutive to a decrease in unsaturated FAS in the absence of panC, we showed that silencing panC extended the destruction time of 16HBE airway cells. Overall, our findings highlighted the anti-virulence potential of panC inhibition and shed new light on its inhibition as a target for treating carbapenem-resistant OprD-defective PA lung infections.

microbiology↗

bioRxiv2022

Faecal carriage of ESBL-producing Escherichia coli in a remote region of Niger

ObjectiveWhole genome sequencing (WGS) of extended-spectrum {beta}-lactamase-producing Escherichia coli (ESBL-E. coli) in developing countries is lacking. Here we describe the population structure and molecular characteristics of ESBL-E. coli faecal isolates in rural Southern Niger. MethodsStools of 383 healthy participants were collected among which 92.4% were ESBL-E. coli carriers; 90 of these ESBL-E. coli containing stools (109 ESBL-E. coli isolates) were further analysed by WGS, using short- and long-reads. ResultsMost isolates belonged to the commensalism-adapted phylogroup A (83.5%), with high clonal diversity. The blaCTX-M-15 gene was the major ESBL determinant (98.1%), chromosome-integrated in approximately 50% of cases, in multiple integration sites. When plasmid-borne, blaCTX-M-15 was found in IncF (57.4%) and IncY plasmids (26.2%). Closely related plasmids were found in different genetic backgrounds. Genomic environment analysis of blaCTX-M-15 in closely related strains argued for mobilisation between plasmids or from plasmid to chromosome. ConclusionsMassive prevalence of community faecal carriage of CTX-M-15-producing E. coli was observed in a rural region of Niger due to the spread of highly diverse A phylogroup commensalism-adapted clones, with frequent chromosomal integration of blaCTX-M-15. Plasmid spread was also observed. These data suggest a risk of sustainable implementation of ESBL in community faecal carriage.

microbiology↗

bioRxiv2021

Origins and breadth of pairwise epistasis in an α-helix of β-lactamase TEM-1

Epistasis affects genome evolution together with our ability to predict individual mutation effects. The mechanistic basis of epistasis remains, however, largely unknown. To quantify and better understand interactions between fitness-affecting mutations, we focus on a 11 amino-acid -helix of the protein {beta}-lactamase TEM-1, and build a comprehensive library of more than 15,000 double mutants. Analysis of the growth rates of these mutants shows pervasive epistasis, which can be largely explained by a non-linear two-state model, where inactivating, destabilizing, neutral, or stabilizing mutations additively contribute to the phenotype. Hence, most epistatic interactions can be predicted by a non-linear model informed by single-point mutational measurements only. Deviations from the two-state model are consistently found for few pairs of residues, in particular when they are in contact. This result, as well as single-point mutation parameters, can be quantitatively found back through direct-coupling-analysis-based statistical models inferred from homologous sequence data. Our results thus shed light on the existence and the origins of the multiple determinants of the epistatic landscape, even at the level of small structural components of a protein, and suggest that the corresponding constraints shape the entire {beta}-lactamase family.

evolutionary biology↗