Here we determined the structure of a cold active family IV esterase (EstN7) cloned from Bacillus cohnii strain N1. EstN7 is a dimer with a classical α/β hydrolase fold. It has an acidic surface that is thought to play a role in cold-adaption by retaining solvation under changed water solvent entropy at lower temperatures. The conformation of the functionally important cap region is significantly different to EstN7's closest relatives, forming a bridge-like structure with reduced helical content providing greater access to the active site through more than one substrate access tunnel. However, dynamics do not appear to play a major role in cold adaption. Molecular dynamics at different temperatures, rigidity analysis, normal mode analysis and geometric simulations of motion confirm the flexibility of the cap region but suggest that the rest of the protein is largely rigid. Rigidity analysis indicates the distribution of hydrophobic tethers is appropriate to colder conditions, where the hydrophobic effect is weaker than in mesophilic conditions due to reduced water entropy. Thus, it is likely that increased substrate accessibility and tolerance to changes in water entropy are important for of EstN7's cold adaptation rather than changes in dynamics.

The Hbl toxin is a three-component haemolytic complex produced by Bacillus cereus sensu lato strains and implicated as a cause of diarrhoea in B. cereus food poisoning. While the structure of the HblB component of this toxin is known, the structures of the other components are unresolved. Here, we describe the expression of the recombinant HblL₁ component and the elucidation of its structure to 1.36 Å. Like HblB, it is a member of the alpha-helical pore-forming toxin family. In comparison to other members of this group, it has an extended hydrophobic beta tongue region that may be involved in pore formation. Molecular docking was used to predict possible interactions between HblL₁ and HblB, and suggests a head to tail dimer might form, burying the HblL₁ beta tongue region.

Introduction: Pseudomonas aeruginosa is widely recognised as theprimary etiological agent for serious infections in burn patients worldwide.Objective: To examine the frequency of the exoU/exoS genotype in clinical isolates of P. aeruginosa obtained from burn wound infections in Iraq and its correlation with antibiotic resistance.Methodology: 80 P. aeruginosa isolates were obtained from patients diagnosed with burn wound infections in Iraqi hospitals. The isolates were initially identified by biochemical methods and subsequently confirmed by molecular techniques. Conventional polymerase chain reaction (PCR) was used to detect the exoU/exoS genotype. Antibiotic susceptibility was determined by the disc diffusion method, and biofilm production was assessed by the microtiter plates method. Results: This study found four distinct genotypes in burn wound infections, with substantial differences (P < 0.001). Most P. aeruginosa isolates form biofilm (96.25%; 77/80) at different intensities, with significant differences (p < 0.05) and a statistically significant correlation with an (exoS+\exoU-) genotype. The (exoS+\exoU+) genotype was more antibiotic-sensitive. While the (exoS-\exoU+) genotype was more antibiotic-resistant than other genotypes. The genotype exoU+\exoS- correlated significantly with fluoroquinolone antibiotic susceptibility, resulting in substantial resistance rates against ciprofloxacin and levofloxacin. While the genotype exoU+\exoS+ showed a statistically significant correlation with susceptibility to cephalosporin antibiotic groups (ceftazidime and cefepime), the sensitivity rate was higher than other genotypes.Conclusion: These results suggested that genotype influences antibiotic resistance, posing a concern, as horizontal gene transfer of the exoU gene can increase antibiotic resistance in P. aeruginosa.Keywords: Pseudomonas Aeruginosa, exoU/exoS Genotype, Type III Secretion System, Burn Wound Infections, Biofilm Formation DOI: https://doi.org/10.24321/0019.5138.202625 How to cite this article:Raouf M A, Auhim H S. Correlation Between the Exou/Exos Genotype, Biofilm Formation, and Antibiotic Resistance in Pseudomonas Aeruginosa Isolated from Burn Wound Infections. J Commun Dis. 2026;58(2):17-27.