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

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.

To in silico characterize the secondary structure, conserved motifs, and stereochemical quality of Esp, and to relate these features to adhesion and biofilm persistence.

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.

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.

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.