Biology subjects

Kieffer, N.

Publications and source records attributed to Kieffer, N..

2 recordsLinked to original sources

bioRxiv2024

Mobile Integrons Encode Phage Defence Systems

Integrons are bacterial genetic elements that capture, stockpile and modulate the expression of genes encoded in integron cassettes. Mobile Integrons (MI) are borne on plasmids, acting as a vehicle for hundreds of antimicrobial resistance genes among key pathogens. These elements also carry gene cassettes of unknown function (gcus) whose role and adaptive value remains unexplored. Here we show that gcus encode phage resistance systems, many of which are novel. Bacteriophage resistance integron cassettes (BRiCs) can be combined and mixed with resistance cassettes to produce multiphage or drug/phage-resistance. The fitness costs of BRiCs are variable, dependent on the genetic context, and can be modulated by changing the order of cassettes in the array. Hence, MIs act as highly mobile, low-cost defense islands. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=150 SRC="FIGDIR/small/601719v4_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@965766org.highwire.dtl.DTLVardef@442763org.highwire.dtl.DTLVardef@7600d4org.highwire.dtl.DTLVardef@13068ca_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOSummary FigureC_FLOATNO Novel phage defense systems identified in Mobile Integrons. We confronted genes of unknown function from mobile integrons against a panel of phage. We characterized 13 Bacteriophage Resistance integron Cassettes (BRiCs) and confirmed their function in Klebsiella pneumoniae and Pseudomonas aeruginosa. Combined with other cassettes, BRiCs produce multi-phage/antibiotic resistance. Additionally, their cost can be reduced in an array. C_FIG

microbiology↗

bioRxiv2024

Anaerobiosis modulates the performance of antimicrobial resistance genes in Enterobacteriaceae

Bacteria must face and adapt to a variety of physicochemical conditions in the environment and during infection. A key condition is the concentration of dissolved oxygen, proportional to the partial pressure of oxygen (PO2), which is extremely variable among environmental biogeographical areas and also compartments of the human and animal body. Here, we sought to understand if the phenotype of resistance determinants commonly found in Enterobacterales can be influenced by oxygen pressure. To do so, we have compared the MIC in aerobic and anaerobic conditions of isogenic Escherichia coli strains containing 136 different resistance genes against 9 antibiotic families. Our results show a complex landscape of changes in the performance of resistance genes in anaerobiosis. Certain changes are especially relevant for their intensity and the importance of the antibiotic family, like the large decreases in resistance observed against ertapenem and fosfomycin among blaVIM {beta}-lactamases and certain fos genes, respectively; however, the blaOXA-48 {beta}-lactamase from the clinically relevant pOXA-48 plasmid conferred 4-fold higher ertapenem resistance in anaerobiosis. Strong changes in resistance patterns in anaerobiosis were also conserved in Klebsiella pneumoniae. Our results suggest that anaerobiosis is a relevant aspect that can affect the action and selective power of antibiotics for specific AMRs in different environments.

microbiology↗