ASYMMETRIC DOMAIN MOBILITY IN PSEUDOMONAS AERUGINOSA GLMS REVEALED BY MOLECULAR SIMULATIONS

Antimicrobial resistance is a global public health problem responsible for high annual mortality rates. Pseudomonas aeruginosa is an important member of this group that significantly impacts human health, especially in hospitalized patients. The number of cases is expected to rise in the coming years, making the search for new therapeutic strategies both urgent and necessary. In this context, the enzyme Glucosamine-6-phosphate synthase (GlmS) is a promising therapeutic target because of its role in cell viability. Thus, the objective of this study was to investigate the behavior of the dimeric structure of GlmS of P. aeruginosa (PaGlmS) using in silico methodologies. Three-dimensional structures of PaGlmS were generated using AlphaFold 2.0 on the ColabFold pipeline. To investigate the behavior of the PaGlmS dimer, we performed five independent 1 μs molecular dynamics (MD) simulations using Amber22, with distinct random velocity initialization. The simulation analysis was conducted using AmberTools, VMD, and MDLovoFit. The model with the highest predicted Local Distance Difference Test (95.6) and Predicted Template Modeling (0.949) scores was selected. To assess the overall structural stability, we monitored the time evolution of the backbone RMSD. In all simulations, the RMSD remained below 3.5 Å. To further characterize domain mobility, we used MDLovoFit to identify rigid and flexible regions. These results indicate that the ISOM domain forms a rigid and stable core in PaGlmS, while the GAT domain exhibits greater conformational mobility. During MD analysis, we observed marked asymmetry in the flexibility of the GAT domains between the two chains of the dimer. This asymmetry was evidenced by RMSF (bfactor) analysis, in which one of the domains showed high flexibility, whereas the corresponding domain of the other chain remained considerably more rigid. Interestingly, the same trend was observed for the three distinct crystallographic structures of Escherichia coli GlmS. These findings agree with those of Mouilleron et al. (2006), who described significant differences in mobility between the GAT domains of the EcGlmS crystal dimers. To investigate this asymmetry, we will submit the new structures of PaGlmS and EcGlmS to MD simulations in the next steps of this study.