A team headed by scientists from the Institute for Research in Biomedicine (IRB Barcelona) reports how the protein Ler, which is found in pathogenic bacteria, interacts with certain DNA sequences, thereby activating numerous genes responsible for virulence, which bacteria then exploit to infect human cells. Ler is present in pathogenic Escherichia coli (E.coli) strains, such as the one that caused a deadly infectious outbreak in Germany last May. The study has been published in the scientific journal PloS Pathogens.
The researchers have solved the three-dimensional structure of a key region of the DNA-protein complex. Knowledge about the structures that control the activity of genes associated with virulence and resistance to antibiotics is crucial to understand the molecular mechanisms that regulate bacterial pathogenicity and to pave the way for alternative treatments to conventional antibiotics. According to Jesús GarcÃa, research associate in the IRB Barcelona group headed by Miquel Pons, researcher at IRB Barcelona and professor of the UB, a strategy based on selective regulatory systems for genes responsible for virulence is particularly attractive because it could potentially minimize the adverse effects on our bacterial flora and reduce the selective pressure for the development of antibiotic resistance in bacteria.
Many of the genes responsible for pathogenic bacteria virulence and resistance to antibiotics have been acquired through processes such as horizontal gene transfer (HGT). By means of this mechanism, bacteria incorporate genetic material from external sources such as bacteria or phages (viruses that affect bacteria). The correct regulation of HGT genes, in other words silencing when not required and coordinated activation to produce a beneficial effect, is crucial for the success of bacteria.
The resolved structure has allowed us to understand the way in which Ler recognizes its DNA binding sites. Ler does not recognize specific sequences but local DNA structures. In our study we also tested whether this recognition mode is used by other proteins of the same family, such as H-NS, explains GarcÃa. The Ler and H-NS proteins play a critical role in the regulation of genes acquired through HGT in pathogenic E. coli strains.
The study forms part of Tiago N. Cordeiros doctoral thesis and has involved researchers from the Institute for Bioengineering of Catalonia (IBEC), the University of Barcelona (UB) and the Max Planck Institute for Biophysical Chemistry in Göttingen.
Reference: Tiago N. Cordeiro; Holger Schmidt; Cristina Madrid; Antonio Juárez; Pau Bernadó; Christian Griesinger; Jesus GarcÃa; Miquel Pons. Indirect DNA Readout by an H-NS Related Protein: Structure of the DNA Complex of the C-Terminal Domain of Ler. PLoS Pathog 7(11): e1002380. doi:10.1371/journal.ppat.1002380
Â
The Next Frontier in Infection Control: AI-Driven Operating Rooms
Published: July 15th 2025 | Updated: July 15th 2025Discover how AI-powered sensors, smart surveillance, and advanced analytics are revolutionizing infection prevention in the OR. Herman DeBoard, PhD, discusses how these technologies safeguard sterile fields, reduce SSIs, and help hospitals balance operational efficiency with patient safety.
Targeting Uncertainty: Why Pregnancy May Be the Best Time to Build Vaccine Confidence
July 15th 2025New national survey data reveal high uncertainty among pregnant individuals—especially first-time parents—about vaccinating their future children, underscoring the value of proactive engagement to strengthen infection prevention.
CDC Urges Vigilance: New Recommendations for Monitoring and Testing H5N1 Exposures
July 11th 2025With avian influenza A(H5N1) infections surfacing in both animals and humans, the CDC has issued updated guidance calling for aggressive monitoring and targeted testing to contain the virus and protect public health.
IP LifeLine: Layoffs and the Evolving Job Market Landscape for Infection Preventionists
July 11th 2025Infection preventionists, once hailed as indispensable during the pandemic, now face a sobering reality: budget pressures, hiring freezes, and layoffs are reshaping the field, leaving many IPs worried about their future and questioning their value within health care organizations.