Crystal structure and functional characterization of SF 216 from Shigella flexneri

Shigella flexneri is a Gram‐negative anaerobic bacterium that causes highly infectious bacterial dysentery in humans. Here, we solved the crystal structure of SF 216, a hypothetical protein from the S. flexneri 5a strain M90T, at 1.7 Å resolution. The crystal structure of SF 216 represents a homotrimer stabilized by intersubunit interactions and ion‐mediated electrostatic interactions. Each subunit consists of three β‐strands and five α‐helices with the β‐β‐β‐α‐α‐α‐α‐α topology. Based on the structural information, we also demonstrate that SF 216 shows weak ribonuclease activity by a fluorescence quenching assay. Furthermore, we identify potential druggable pockets (putative hot spots) on the surface of the SF 216 structure by computational mapping.