Mechanism Of ATP Hydrolysis By The Zika Virus Helicase

Zika virus?ZIKV?is an arthropod-borne flavivirus.It can cause microcephaly in newborn infants and Guillain-Barrésyndrome,threatening human health all over the world.There is no specific therapy available to treat illnesses caused by ZIKV.ZIKV helicase performs ATP hydrolysis to generate energy and thus sustains unwinding of double-stranded RNA,playing a critical role in ZIKV genome replication.Of these processes,ATP hydrolysis represents the most basic event;however,its dynamic mechanisms 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.These structures represent the intermediate state and post-hydrolysis state,respectively,of the ATP hydrolysis process.These findings,together with our earlier work,which identified the pre-hydrolysis state of ZIKV helicase,lead to a proposal of the ATP hydrolysis cycle for ZIKV helicase.On this basis,we employed site-directed mutagenesis combined with an enzymatic study to successfully identify residues that are critical for the ATPase activity of ZIKV helicase;this will provide new ideas to understand the function for the key enzyme of ZIKV and aid in the development of inhibitors targeting the important points of ZIKV.