Structural insights into choline-O-sulfatase reveal the molecular determinants for ligand binding
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AuthorGavira Gallardo, José Antonio; Torres De Pinedo, Jesús Manuel; Sánchez Medina, María Pilar; Ortega Sánchez, Esperanza; Martínez Rodríguez, Sergio
International Union of Crystallography
CholineSulfatasesConformational gatingAlkaline phosphatasesPromiscuity
Gavira, J. A... [et al.]. (2022). Structural insights into choline-O-sulfatase reveal the molecular determinants for ligand binding. Acta Cryst. D78, 669-682. [https://doi.org/10.1107/S2059798322003709]
SponsorshipSpanish Government European Commission PID2020-116261GB-I00 RTI2018-097991-B-I00; Secretaria General de Universidades; Junta de Andalucia PY20-00149 UAL18-BIO-B005-B; University of Granada PPJI2017-1
Choline-O-sulfatase (COSe; EC 126.96.36.199) 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 (Asn146A–Asp500B–Asn498B). 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 A ° ). 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.