Antibiotic resistance currently represents one of the greatest threats to public health worldwide and has an impact on the economics of the agricultural and food sector. Foodborne pathogens such as Escherichia coli and Salmonella enterica (Enterobacteriaceae family), which cause diarrheal diseases, urinary tract infections and sepsis, generate high mortality rates worldwide, with special concern for bacteria resistant to carbapenemics (antibiotics with the broadest spectrum of activity which are considered antibiotics of last resort).

Elongation and division of peptidoglycan are the source of main antibiotic targets. Although through structural modifications certain antibiotics have increased their affinity, the search for new drugs and targets has become urgent to cope with the constantly evolving mechanisms of resistance. This highlights the need to study the coordination of enzymatic activities involved in these processes and in the biogenesis of inner and outer membranes. Likewise, preseptal growth (peptidoglycan synthesis prior to septation at the division site), essential for cell viability, remains poorly characterized.

Multiple pathogenic bacteria show morphological plasticity, constituting elongated multinucleated structures and evading the immune system during infection. However, molecular mechanisms of this filamentation or how they impact their virulence remain unknown.

Therefore, this line of research aims to use Escherichia coli as a working model to identify protein interactions involved in preseptal cell wall growth and their impact on peptidoglycan homeostasis and outer membrane stability by deletion analysis with a multicopy genomic DNA library and the construction and screening of a transposon library. We will also determine novel protein interactions, their impact and localization using purified proteins and/or in vivo and in vitro cross-linking methods coupled to mass spectrometry.

By applying the results to pathogenic strains (uropathogenic E. coli or S. enterica) we will establish the role of preseptal growth in bacterial virulence and as a possible new antibiotic target, increasing the relevance of our results in the fight against antibiotic resistance. Through the reconstruction of mutant strains (recombination and conjugation methodology), we will study the preseptal growth-virulence genetic correlation (in vitro approaches - polymyxin B resistance, biofilm formation...- and cell culture based - macrophage proliferation or HeLa cell invasion assay).