Resumen: Choline-O-sulfatase (COSe; EC 3.1.6.6) is a member of the alkaline phosphatase (AP) superfamily, and its natural function is to hydrolyze choline-O-sulfate into choline and sulfate. Despite its natural function, the major interest in this enzyme resides in the landmark catalytic/substrate promiscuity of sulfatases, which has led to attention in the biotechnological field due to their potential in protein engineering. In this work, an in-depth structural analysis of wild-type Sinorhizobium (Ensifer) meliloti COSe (SmeCOSe) and its C54S active-site mutant is reported. The binding mode of this AP superfamily member to both products of the reaction (sulfate and choline) and to a substrate-like compound are shown for the first time. The structures further confirm the importance of the C-terminal extension of the enzyme in becoming part of the active site and participating in enzyme activity through dynamic intra-subunit and inter-subunit hydrogen bonds (Asn146(A)-Asp500(B)-Asn498(B)). These residues act as the ''gatekeeper'' responsible for the open/closed conformations of the enzyme, in addition to assisting in ligand binding through the rearrangement of Leu499 (with a movement of approximately 5 angstrom). Trp129 and His145 clamp the quaternary ammonium moiety of choline and also connect the catalytic cleft to the C-terminus of an adjacent protomer. The structural information reported here contrasts with the proposed role of conformational dynamics in promoting the enzymatic catalytic proficiency of an enzyme. Idioma: Inglés DOI: 10.1107/S2059798322003709 Año: 2022 Publicado en: Acta Crystallographica Section D-Structural Biology 78 (2022), 669-682 ISSN: 2059-7983 Factor impacto JCR: 2.2 (2022) Categ. JCR: CRYSTALLOGRAPHY rank: 11 / 26 = 0.423 (2022) - Q2 - T2 Categ. JCR: BIOCHEMICAL RESEARCH METHODS rank: 55 / 77 = 0.714 (2022) - Q3 - T3 Categ. JCR: BIOPHYSICS rank: 48 / 70 = 0.686 (2022) - Q3 - T3 Categ. JCR: BIOCHEMISTRY & MOLECULAR BIOLOGY rank: 241 / 285 = 0.846 (2022) - Q4 - T3 Factor impacto CITESCORE: 7.5 - Biochemistry, Genetics and Molecular Biology (Q2)