Mechanism of ATP hydrolysis by the Zika virus helicase

Abstract

During its life cycle, Zika virus (ZIKV), an arthropod-borne flavivirus that is associated with Guillain- Barré syndrome and causes microencephaly in fetuses and newborn children, encodes a critical and indispensable helicase domain that has 59-triphosphatase activity and performs ATP hydrolysis to generate energy and thus, sustains unwinding of double-strandedRNAduringZIKVgenome replication.Of these processes,ATP hydrolysis represents themost basic event; however, its dynamicmechanisms remain largely unknown, impeding the further understanding of the function of ZIKV helicase and the ongoing anti-ZIKV drug design. In this work, we determined the crystal structure of ZIKV helicase in complex with ADP-AlF3-Mn2+ and ADP-Mn2+ separately. The structural analysis indicates that these structures represent the intermediate state and posthydrolysis state, respectively, of the ATP hydrolysis process of ZIKV helicase. These findings, together with our earlier work, which identified the prehydrolysis state ofZIKVhelicase, lead to a proposal of theATP hydrolysis cycle forZIKVhelicase. On this basis, we used site-directed mutagenesis combined with an enzymatic study to identify successfully residues that are critical for theATPase activity ofZIKVhelicase; thiswill provide new ideas to understand the function for the key enzyme of ZIKV.