Sulfated PSGL-1 primes the enterovirus A71 fivefold vertex for localized remodeling

Enterovirus A71 (EV-A71) causes hand, foot, and mouth disease and poses a significant public health threat through severe neurological complications in pediatric cases. P-selectin glycoprotein ligand-1 (PSGL-1) functions as an attachment factor, yet the structural basis of PSGL-1 recognition on the EV-A71 capsid has remained undefined. Here, we use cryo-EM to compare a PSGL-1–non-binding EV-A71 strain (EV-V) with a PSGL-1–binding strain (EV-R) and analyzeEV-R particles incubated with a sulfated 20-residue PSGL-1 N-terminal peptide (sPSGL-1; residues 42–61). In EV-R, a VP1-145 substitution disrupts the interprotomer E145–K244 interaction, repositions K244, and increases local electrostatic potential at the fivefold vertex. A fivefold-focused, symmetry-relaxed (C1; no symmetry imposed) 2.38 Å reconstruction reveals low-occupancy, vertex-adjacent densities associated with sPSGL-1 incubation, including a locally interpretable density feature consistent with an aromatic ring near VP1 K244, together with localized structural differences in VP1 loops and pocket-adjacent regions. The pocket factor and VP4 remain present, and electrostatic mapping localizes this signal within a lysine-rich vertex cleft. These observations are consistent with localized fivefold-vertex priming without evidence for an uncoating-associated A-particle transition within the compact/closed population analyzed. Cryo-EM reveals how sulfated PSGL-1 engages the EV-A71 fivefold vertex through electrostatic interactions, priming localized structural changes that facilitate early-stage receptor recognition without triggering global uncoating.