DECIPHERING MORPHEEIN TRANSITIONS IN PSEUDOMONAS AERUGINOSA GLMS: REVEALING A NOVEL MECHANISM FOR ANTIBACTERIAL INTERVENTION

Antimicrobial resistance is a critical global health threat, and Pseudomonas aeruginosa is a leading cause of difficult-to-treat infections in hospitalized patients. Glucosamine-6-phosphate synthase (GlmS) catalyzes the first committed step in the hexosamine pathway and is essential for bacterial cell wall biosynthesis, making it an attractive antibacterial target. In Escherichia coli, GlmS exhibits morpheein-type allosteric regulation, interconverting between an active dimer and an inactive hexamer. However, the conformational landscape of P. aeruginosa GlmS (PaGlmS) and its oligomerization transitions remain poorly understood. This work aims to elucidate, in silico, the structural determinants that govern the transition between active and inactive conformers of PaGlmS, providing a framework for allosteric drug design that stabilizes inactive states. Comparative models of PaGlmS were generated with MODELLER 10.0 using E. coli GlmS templates: an active dimer (PDBid 4AMV; Fru6Pbound) for apo and holo dimeric models, and the C1A mutant hexamer (PDBid 3OOJ) for an inactive-like conformer. To probe dimer dynamics, we performed five independent 500 ns all-atom molecular dynamics simulations per ligation state with Amber22 in explicit solvent, each initialized with distinct random velocity seeds. Trajectory analyses will be carried out with AmberTools, VMD, MDLovoFit, and related tools to (i) define collective variables that distinguish active-like and inactive-like dimers (e.g., interdomain distances and dimer twist angles, helix CF position, key catalytic distances), (ii) construct free-energy landscapes along these coordinates, and (iii) apply essential dynamics and clustering to identify dominant conformational substates and domain communication networks. Preliminary analyses reveal increased flexibility of the interdomain linker and suggest that the conformational ensemble is organized into two dominant basins corresponding to active-like and inactive-like states. Attention will be given to the linker and regulatory loops that couple glutaminase and synthase domains, and to the comparison between PaGlmS and EcGlmS. We expect these simulations to reveal how intrinsic dynamics bias PaGlmS toward active or inactive dimeric states and to highlight transient allosteric pockets that could be exploited to trap the enzyme in an inactive conformation. The resulting structural and thermodynamic insights will support future structure-based design and virtual screening campaigns targeting PaGlmS oligomeric regulation in multidrugresistant P. aeruginosa.