Sequence-based structural/motif and stereochemical analysis of enterococcal surface protein in endodontic

Background: Enterococcus faecium synthesizes enterococcal surface protein (Esp), a cell wall-anchored, domain-adhesin implicated in healthcare-associated infections and persistent root canal disease. Esp may facilitate the development of strategies to inhibit surface attachment and decrease biofilm formation. Aim: To in silico characterize the secondary structure, conserved motifs, and stereochemical quality of Esp, and to relate these features to adhesion and biofilm persistence. Materials and Methods: The Esp sequence was analyzed using Garnier–Osguthorpe–Robson (GOR) secondary structure prediction, motif and feature annotation, and stereochemical evaluation via Ramachandran plots and the overall G-factor. The study had an assessment of α-helices, β-strands, β/γ turns, β-hairpins, and immunoglobulin-like repeats. Structural quality was defined by the proportion of favored conformations and backbone geometry metrics. Results: Esp is predicted to form a mostly β-sheet based structure with 35 α-helices, multiple turns, and recurring β-hairpins, consistent with Ig-like modules; stereochemical analysis (85% residues in favored Ramachandran regions; G-factor −0.33) supports acceptable backbone geometry, and the abundance of turns/hairpins likely provides flexible interdomain linkers that promote surface binding and biofilm stability under root-canal stress. Conclusion: Sequence-based structural/motif and stereochemical analyses suggest that Esp adopts a flexible, β-rich scaffold with recurrent turns and hairpins that may support adhesion and biofilm persistence in endodontic settings.