<div><p>The surface protein SdrE, a microbial surface components recognizing adhesive matrix molecule (MSCRAMM) family protein expressed on the surface of <i>Staphylococcus aureus</i> (<i>S</i>. <i>aureus</i>), can recognize human complement regulator Factor H and C4BP, thus making it a potentially promising vaccine candidate. In this study, SdrE<sup>278-591</sup> was found to directly affect <i>S</i>. <i>aureus</i> host cell invasion. Additionally, the crystal structure of SdrE<sup>278-591</sup> at a resolution of 1.25 Å was established, with the three-dimensional structure revealing N2-N3 domains which fold in a manner similar to an IgG fold. Furthermore, a putative ligand binding site located at a conserved charged groove formed by the interface between N2 and N3 domains was identified, with β2 suspected to occupy the ligand recognizing site and undergo a structural rearrangement to allow ligand binding. Overall, these findings have further contributed to the understanding of SdrE as a key factor for <i>S</i>. <i>aureus</i> invasivity and will enable a better understanding of bacterial infection processes.</p></div
